Because everyone secretly wants to be a hot chick.
ROFL! You almost made me spew my Dr. Pepper (the REAL Dr. Pepper with REAL sugar) all over the keyboard!
To be sure, I do not look ONLY for games that are typically refered to as "female friendly". Ultimately, if the game fails to get my interest based on story, graphics and depth, it isn't worth my time anyway. Being female friendly is just a welcome bonus in my opinion, and will result in my being "drawn" into the story further.
With budgets as tight as they are for consumers, (and indeed mine is - I have two teenage gamers to also buy for), I have to make tough choices on games I purchase for myself. Truthfully, a game must have 90% of the elements I look for. Skyrim fit that bill VERY well.
Also, I don't have a "problem" playing a male character. It is just nice if I have an option. As far as on line gaming... I have been known to pretend to be a male player who is playing a female character simply to avoid the bother of what usually goes on in the culture.
If they think I am a guy, they don't bother me. I don't want to be hit on, I don't want to be hassled, I don't want to be treated differently or given anything... I just wanna play the game.