I think the colours and bedroom / clothing conventions a kid is borne into are probably less damaging than the horrible attitudes they would have been exposed to - even only in the 70s or 80s - which isn't that long ago.
I don't have kids myself, but I have a young nephew. I remember being out with my sister and him when he was about 2/3 and we'd explained Halloween to him, and that he could pick a costume from the store we were in -- he pointed towards and asked for a Princess costume. Me and my sister looked at each other amused, but speaking about it afterwards we were kinda like 'why the fuck not, let him wear what he wants to wear - he's still young enough that no-ones going to give him shit for it'. He eventually picked Spiderman, but that's besides the point. Our attitudes would have been non-existant in the past.
Having a youngun' in the family has made me reconsider some views though. I've always held that videogames are harmless, and I'm sure they're as harmless as any other form of media... but I've definitely observed something I never noticed in my own life. You can sit my nephew in front of his hero, Spiderman, and he'll be hard to get through to -- but he'll be able to hear you. Sit him with a 3DS in his hand playing Fireman Sam or Mario, or stick a phone in his hand with Angry Birds or whatever -- he literally cannot hear you. Its made me reconsider what this does to the social lives of young people. Its like they haven't grown the multitasking ability yet, the ability to be fascinated and yet open to external action... he becomes, literally, zombie like.
I'm sure I was the same in the 80s/90s, but seeing it is disturbing. I can see why parents worry. When he comes to my house to visit he always wants Mario or Sonic Racing, or to watch comic superheroes on Netflix.. I find myself torn between allowing it, because I had it, and trying to coax him outside -- which I never really did myself