I know a man who chose female Shepard for the sole purpose of hearing Jennifer Hale's voice....actually, that's a bit naive...he probably also did so for the view, as many have already stated.
I, as a woman, try to play a game through a game with both male and female avatars. If the game is simply not worth playing twice...I'll be honest, I'm usually a guy. This is due to the fact that they are often the first section a dev team works on, and the female equivalent is often done second, and if not, as an afterthought. If there are two genders to play, I'll usually pick male and then female. I'm not claiming sexism here, it's just often the progression of development. You'll notice that, in these cases, a lot of games use the same dialogue/script for both scenarios...The only difference being that they make less sense due to the protagonist's gender.
These instances have the potential to be nothing short of hilarious; see "female Shepard sitting with skirt." The first word that comes to mind is "inviting."
Also, I am aware of the fact that the number of exceptions grows with rapid succession.