Playtime allows boys and girls to construct a fantasized version of what their life will be like when they get older. Boy play usually involves good versus evil. Boys want to occupy the good character, destroy the bad character, and assert their power over the world. For girls, occupying the role of observable adult women is more attractive. That's why we have Teacher Barbie, Astronaut Barbie, and Doctor Barbie.
Girls also play more cooperatively.
A group of girls will often agree on a joint goal and work toward it. When you get a group of boys together, they generally agree on a game with rules, and one will come out with the most points and win. Media in general has been accused of promoting sex stereotypes. We're very pragmatic. We design an awful lot of toys compared with the number we actually release.