Player2 on 06 August 2013
Because teens like to identify themselves with the cool lead character, and they can't if it's a girl.
This isn't anything new. Back then in the arcade days in Golden Axe people choosed to play as Ax Battler (the blue guy) instead of Tyris Flare despite him being way worse. And you had to hear comments like "Ha-ha, you're a girl!" if you dare to choose Tyris.
