I completely believe that keeping yourself covered adds mystery and allure, but in today's internet-ready, stalkerazzi-friendly society nothing is sacred. Flashing a boob is pretty standard and with all those little starlets running around without underwear... well you get the point.
The female form is such an artistic standard that even us up-tight North Americans have accepted its' prevalence in mainstream culture and to show it in all it glory is hardly subversive anymore. The exposure of the male form, however, has not enjoyed such a North American liberation. A penis is an automatic NC-17. I guess that's what you get when society has been and continues to be run by a bunch of out-of-touch misogynistic afraid-of-the-gay born-again neo-cons.