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.

I agree, but I really don't understand how or why scientifically minded people could claim that they believe male and female brains to be absolutely biologically identical.

We evolved to have specific gender roles. We have obvious physical differences related to those roles. We have obvious psychological differences as well.

I can only imagine that to some people, the truth is inconvenient to them in their "everyone is absolutely identical" utopia.

I'm no proponent of "everyone is absolutely identical", but I would go with "everyone is absolutely much more similar than the cliches pushed by e.g. the toy industry". The role of cultural influence in this is enormous and impossible to separate from intrinsic biological differences. I'm from New Zealand where (at least in my peer group) gender roles are not too clearly defined. However I live in Spain where they absolutely are - are New Zealanders biologically less sexist than Spaniards? Of course not.

There's another interesting discussion to be had around brain plasticity and whether people raised in cultures which promote differences are actually more different, but I'm not aware of research in this area. It would be interesting to see.

Right, but before WWII, pink was a boy's color and blue was for girls.

Few here are saying that brains are entirely identical, but the fact is you cannot overlook cultural aspects. These aspects are at best only loosely tied to biology and many are purely arbitrary (such as color preferences).