Falling Skies/WMG

NOTE: Please put WMG's in the appropriate part of the season, this permits people watching the series on DVD (when it is released that way) to read a few WMG's as they go rather than having to wait until they are entirely caught up first.

The Skitters are a former slave race that broke out of bondage and appropriated most of their previous masters' technology to become the force they are today.
Why do the Skitters have bipedal mechs? Well, maybe they once were the conquered instead of the conqueror, but they overthrew their masters and stole most of their technology. The Mechs are bipedal because their masters were bipedal, and the harnesses were originally mind-control devices kept to keep the Skitters in line.

The harnessed children are being used to create mechs.
That's why the mechs are bipedal: they're build around children, who are the control centres. The scrap metal is being collected so that it can be used in the construction of more mechs. The harnesses have some kind of telepathic connection to the skitters, so that the skitters can control the mechs.
 * Still, this is possible.

Mechs are operated by aliens, but not skitters.
A different alien species conquered the skitters, who are now being used as cannon fodder on Earth.

The aiming problems with mechs are glossed over/ignored by their already-busy R&D by just adding more laser sights
There are several laser sights for one gun on a mech, and they still have trouble hitting moving targets. "Distracted Engineer Skitter: Oh, we'll just put another laser sight on it, maybe that will work this time."

Skitters are incapable of having offspring
That is why their forces on Earth are limited and one of the reasons why they take children.

Collecting scrap metal is practice for shooting humans
From a logical point of view, if you have a mind control device, then you've still got the hardest part to do: Creating the mind control program. The skitters (or their alien overlords) might still be experimenting to see how much they can get away with. Collecting scrap metal is a good field test, as it requires some rather sophisticated behaviors. Independent navigation. Differentiating scrap metal from non scrap metal. Understanding how to dismantle it. Taking it to a central point, in one case as part of a relay. Many of these behaviors (especially hunting, and target profiling) are vital steps towards an autonomous fire control system. EG: What you need to run a hunter/killer 'terminator'.

Obligitory reference to Time Lords, Haruhi, Everyone Is Jesus in Purgatory, etc, etc, etc.

 * Now can we please move on?

The Mechs are a conquered slave race.
Assuming that the Mechs aren't really us being turned into mechs, the whole "Bipedal Locomotion" thing doesn't quite jive with the fact that Skitters have lots of legs. Perhaps they were another race that encountered the Skitters long ago, and were conquered and enslaved?

Neither the Mechs nor the Skitters are conquerors.
Related to two of the above. The Skitters and Mechs are both enslaved by and subordinate to a higher caste of entirely different aliens like the members of The Combine are to the Advisers.

The harnesses turn people into Skitters, and Earth is a Skitter farm.
Bear with me for a moment, as this idea is rather convoluted. The Skitters were at one point just your average race of colonial aliens, but something or other caused a rather perpetual war with another race. Feeling desperate, they devised a plan. Because cloning themselves is expensive and inefficient, they made a way to turn other races into them, the harnesses. The harnesses slowly and steadily alter DNA and body structure until whatever they're altering becomes a rather rough facsimile of a Skitter. The skitters found Earth and decided it was the perfect breeding ground for their little project. Every time the Human population gets to high, or the Skitter population gets too low, they come and harvest the fruits of the Earth, kill off civilization, and reintroduce life to the planet. They do their best to keep their images from showing up in mythology and history, but occasionally something gets through, and never enough to give Humanity cause to prepare.
 * This looks to be confirmed, after the "What Hides Beneath", when they did an autopsy of a Skitter and found a harness inside it.
 * Wow, a theory of mine actually possible? I may as well expand on it a little. The tall aliens are at war with something or other, the skitters are their ground troops, something ELSE pilots their aircraft, and there are multiple varieties of harnesses for making various kinds of slaves.
 * The final episode of the first season showed Rick wall-crawling like the skitters do, and the girl at the end said that the harnesses were just part of a process. There was also another girl who talked to Rick who showed much more of the transformation process, part of which seems to involve growing an exoskeleton.
 * Alternately, the Skitters are a transformed version of a benign race of many-legged aliens, which the Slenders conquered and equipped with harnesses and exoskeletons to use as cannon fodder in their invasions of other worlds. In future seasons, we might see some of the un-transformed versions fighting back against the Slenders and their slaves, just like the humans are doing.

The harnesses turn people into Skitter-human hybrids, and Earth is a Skitter colonization project.
Mike's son Rick talks like he's an alien now, no longer a human, and the promo for next week seemed to show some sort of new hybrid alien.
 * The final episode of season one confirmed that Harnesses are part of a process, and that removing them does not stop the process.

The Skitters are dying, and are taking the children to preserve their race.
This is related to the above theory: something (be it a bioweapon or a virus, or something like that) has left the Skitters all sterile, and they're taking the children to replenish their species. The way this works it that the harnesses change the children into Skitters -- it was stated in "Grace" that the harnesses grow into their hosts, and Ricky and Ben's were in them long enough for their spikes to stay permanent. If the harnesses stay in long enough, they begin to change the biology and mentality of their hosts to match that of the Skitters. But they also don't work on adults for some reason, which is why only children are taken.
 * Presumably, they work best on younger children, as they aren't fully developed. Because they are still growing, it is easier to change how they grow in order to make them into skitters. Babies would logically work the best, and teenagers the worst. (Excluding adults, as they aren't in a state of proper growth by then.)

The new, tall aliens are actually the end result of harnessing humans.
The skitters are the end result of their own race's harnessing.

The harnesses are the true masters here.
The harnesses are Puppeteer Parasites that are really running things.

Falling Skies is set in the same universe as Close Encounters of the Third Kind.
The tall aliens look like the tall aliens from the movie. After the aliens had the peaceful meeting in Wyoming in the 1970's, they backed off and planned their invasion. (And Steven Spielberg is involved with both works, too!)
 * So all we're missing is a child looking at the mechs and saying, "Toys!"
 * The five planes returned at the beginning of CE3K had been missing since 1945, and they were returned 30 years later in the 1970's. The events of Falling Skies happen 30 years after the 1970's. Looks like that's the travel time to their homeworld.

The aliens hate dying.
The aliens show an unwillingness to fight the humans in situations where they might not take the humans by storm. They nuke Boston when Reed uses a couple AT 4 s and it is implied they nuke any gatherings of humans they deem to be too large. When they engage, they send only a few mechs to fight, thus saving themselves from any real harm.

Rick, when he was still under the affects of the harness, spoke about humans killing each other with disdain, insistent that the aliens would not do such to each other.

The captured skitter goes berzerk when he sees the body of his comrade.

They expected for the rest of humanity to give in and be cowed by the initial assault, because they would have been. That's why they find the resistance to be "interesting" and want to negotiate despite still having an overwhelming advantage.

The new armor piercing rounds might even inspire the skitters to stop fighting the humans outright and to just nuke every major resistance holding.

The entire show was made after Spielberg wanted to turn the Transformers Film Series into a live action TV show
Aliens invade, they want slaves, they kill a bunch of them to establish who they are, they ocupy large cities, they're willing to make deals with humans, and they keep gunships flying about. In the third transformers film, the Decepticons invade, their goal is slavelabour, they kill a bunch to establish who they are, they take over a large city, they make deals with a human and his father, and they have gun ships flying about. Basically what I'm saying is, Spielberg read the skript for DOCT, thought 'hey, this would make a cool show'. He decided to reuse ideas, but for obvious, lawyer related reasons, couldn't use robots. So he got some ideas rolling about radio wave using bug people and tall skinny dudes.

The Harnesses are cyborg implants designed to create super beings for slavery
The Slimmers go to planets with large populations, and start harnessing them. They started with some bug people, and then use them to enslave humans. The harnesses improve the body while also turning them into wall crawling exoscekital lizard people. That's what we know, what we don't know, is the specifics. I'm thinking that, the harness uses its implant parts to inject into the body a series of chemicals to alter the DNA, cells, and anatomy. They cause scales to grow, forming an exoskeliton around the body and the harness that will leave them impossible to remove. They also grant wall crawling abilities, increase their brain's capabilities, and their physical atributes. They then by hijacking the nervesystem, they create a radio transmitter inside the victims body that is conected to their thought process. After a ehile, the Harnessed indavidual starts to crave the experience of the harness, and as such become fiercly loyal to the Slimmers, even after they're no longer being controlled or even Harnessed. The skitters were a race of bug people who lived peacfully, just like humans, until they were taken over and harnessed. Then, to Kick the Dog, they make the Skitters do the exact same thing to another race: Us. This is why the Skitters act so caring for the children, now that they've been taken over, whatever was left of their consciousness causes them to care for the human slave children. The Harnessed children won't turn into Skitters, but they will grow exoskelitons and wall crawling, and even possibly biological radio transmitters.

They could make a radio jammer sugested by someone on a different page with a downed Mech.
If they can take down more mechs without doing too much damage, they can have a look over the mech. Once they do, they could find its radio transmitter that controls it, and use this to make a jamming frequency to take out their comunications with each other, effectivly crippling their forces. Then its only a matter of time before the invaders colapse.

Season two will start off with Tom Mason being found and remembering nothing of his time with the slenders.
Because my Troper-sense is Genre Savvy. He'll learn/figure out more as time goes on. They're not going to give us a Plot Dump right off the bat. We know better.