This exact question was asked in an episode of "Coupling" and the rightful answer goes something like this:
"I like naked women. I'm a bloke. I'm supposed to like them. We're born like that. We like naked women as soon as we're pulled out of one. Halfway down the birth canal we're already enjoying the view. I want to spend the rest of my life with the woman at the end of that table there, but that does not stop me wanting to see several thousand more naked bottoms before I die, because that's what being a bloke is. When man invented fire, he didn't say, "Hey, let's cook." He said, "Great, now we can see naked bottoms in the dark." As soon as Caxton invented the printing press, we were using it to make pictures of, hey, naked bottoms! We have turned the Internet into an enormous international database of naked bottoms. So you see, the story of male achievement through the ages, feeble though it may have been, has been the story of our struggle to get a better look at your bottoms."