People have females as their avatars because they like looking at women.
durrrr
This.
Most of the time in RPGs I pick a female character because I'd much rather be looking at a girl's back. Just like anything else, your "avatar" is never an avatar per se, it's who you want to be looking at the entire time your playing. Only people who want to really get into roleplaying are going to model their avatar after themselves.
It's the same reasoning for having a female scout skin in TF2, and even more so because 90% of the other players aren't going to see you as the female scout, so it's only for your own benefit.
