I think that the general idea is that if a girl wants to play with 'boy' toys, people shouldn't look at her weird like there's something wrong with her. If boys and girls in general will trend to certain types of toys, that's ok. It's the "Billy is playing with dolls, let's make fun of him" or "Billy is playing with dolls, let me beat the crap out of him because I don't want no gay son" attitudes that we want to discourage.