I'm going to say it right off the bat: While I'm not always supremely confident in my theories or ideas, this one is pretty low down.
What's sexy or beautiful? I see two generic physical sources, so no cultural influences like wealth, power, that sort of thing, meaning that I am after what makes a person beautiful given no other knowledge about them. One is overall shape, the other is the face.
I'm theorizing that given equal coverage with clothes, a woman's shape is more noticeable. In other words, even if they are both covered in head to toe armor, a woman will still curve while men do not have something to match unless the armor is tights. In other words, given a ban on nudity, men cannot display a comparable proportion of their uh, shape.
In contrast a face can be rendered with no issues about nudity or indecency, at least as long as the Taliban isn't designing the models. So a male and female face can be equally beautiful. But artists and technicians are still working out the technology to make a sufficiently realistic face which doesn't get stuck in the uncanny valley of being creepy as hell.
Or to express it mathematically, given current technology and obscenity laws:
BodyMale < BodyFemale
FaceMale = FaceFemale
BodyMale + FaceMale < BodyFemale + FaceFemale
In other words, game developers cannot make hot men.