It's all very well for people who, like me, say 'I don't give a shit what they say, if my son wants to play with dolls/daughter wants to play with cars, he/she can', but society, unfortunately, can have a pretty dim view of these things.
My DS loves to walk around in his sister's dress-up shoes, little slip-on shoes with heels and sparkles and stuff. It makes me giggle, an act which in itself is a display of social norms, letting people know that I know that this is an unnatural act.
My DP expresses concern in his 'oh ffs.' This is his way of telling society that he knows it is unnatural too. Neither of us actually care about what he plays with, as long as he is happy. Neither of us really believe in the idea that one toy should be for a girl and not a boy and vice versa, but we are both aware that this is not how society behaves and society is slow to change.
So, if he still wants to play with high heels and princess/fairy wands at the age of ten, we know we have to be prepared for the treatment he will receive from his peers. This is why the gendering of toys is wrong.
Maybe when my DCs have DCs of their own, they will be able to continue past babyhood playing with anything they chose to without any fear of any kind of stigma. Maybe then a girl will be able to say that, when she grows up, she wants to be a plumber, with none of her peers mocking her or a boy can tell his friends, without worrying about their reaction, that he wants to become a nurse. Maybe then the idea of worrying about equal rights will be the thing that gets strange looks, because it's completely unnecessary to worry about it.