Because warlock robes look weird on the male models. That's my excuse for this game anyway. In Dead Island I played as a woman because she had the perks I liked. In the Souls games I play as a woman because smaller hit boxes, I mean, the hit boxes probably aren't smaller but they feel smaller because slimmer looking character. Fallout I play as a woman because Black Widow and Cherchez La Femme. Either way it's pretty much irrelevant unless there are bonuses for being either gender.