Meh, I think it's got alot to do with aesthetics as well. I think it's also got alot to do with male angst. People play games to escape all the bullshit of real life, and males (who identify with the common male engenderment) want to play a character far removed from their suit wearing, high culture lifestyles and adopt an alien persona where they can shoot, stab, and otherwise blow shit up and be someone completely different for atleast an hour or two.
So of course, because most people can't ameliorate their wish to blow up, stab, beat, shoot people/buildings/tanks/etc will create a female character is it allows them to escape their realities for a moment.
Picture it like this ... you wear a suit and a tie to work, then you go to a pub to have a quiet drink and a meal with colleagues to discuss work related stuff, then you go home and want to play videogames to escape all that crap ...
The last thing you want to be reminded about is how you could never be that person that saves millions of people and destroys entire planets when playing a videogame, and I think this affects men more than women. So they create a female character in order to escape comparison to both themselves and their normal lives beyond the game.
In order to enhance escapism, rather than be constrained more and more by their expected personas.