Male Frontal Nudity/Headscratchers

What I don't understand about this trope is why do so many people believe it's gross, when naked women are shown all the time, everywhere and I don't hear anybody complaining. I mean, aren't women supposed to be attracted to the male body? What's the real deal with the fear of seeing a nude guy?
- Because only men seek entertainment. Chick Flick? What's that? No seriously, apparently whenever a man is nude on-screen it's either funny, gross, or both because male audiences are generally more sought after (particularly male 18-34) than most other demographics. Why? Heaven help me, but I have no fucking idea. Though, as a male troper myself I find male nudity far preferable to female nudity.
The main page states that many writers,viewers and producers believe that seeing a penis other than their own will turn them gay... If this is all it takes to "make someone gay" wasn't it because the person was closeted to begin with?
Well, as a female troper I must say that I really do find the usually-concealed bits of male anatomy to be rather unappealing to look at. I find other aspects of the male body attractive, just not that one. Admittedly, I am also not-quite-Asexual (I have no sex drive, but still find people attractive), so mine may not be the opinion you're seeking here. Also, female genitalia are internal and therefore more discreet than male genitalia, thus making even female frontal nudity not show shocking naughty bits unless specifically posed to do so. Also, being attracted to an aspect of a person doesn't mean you want it shoved in your face. Surprising things are surprising (not to be a Captain Obvious), and most occasions of this trope I've seen specifically occur in situations where the nudity is not something the observer wants to see at that time.