Because naked men are ugly; no matter what kind of shape they're in, all men look funny and ungainly without pants. The female form is more graceful and appealing. If I had to choose between staring at Ron Jeremy nekkid or Salma Hayek, I'd go with the girl.
Elaine on Seinfiled had a good bit about the nekkid male body. I think most women would echo your thoughts and its not because there are any sexual tendencies one way or the other.
Yeah, now that you mention it, my idea of a sexy guy is either in faded blue jeans or a tuxedo -- never au naturel. I don't get why European men are so hooked on Speedos. Even guys in great shape look gross in them.
If you really want to drive me insane with passion, a guy needs to say something like...
Honey, you look tired. Want don't you put your feet up and read while I ... (cook dinner, clean the house, care for the kids)
Honey, Let's talk. I want to hear about your day.
Playoff game? What playoff game? You're more important to me than (football, basketball, competitive bobsledding)
Wait. Maybe I AM a lesbian. I obviously want a woman.
Me, too. Nothing pretty about a naked man.