Its not the colour that is the problem. Its the feeling that you need to conform to certain standards within society. The fact that these standards exist at all is the real issue.
There are a limited number of places that don't have the pastel pink and blue aisles of doom. Its marketing. Brands have realised they can sell more by creating the blue for boys, pink for girls thing. People feel like they can not use the pink clothes they had for their daughter when they then have a son. Therefore they go out and buy more. There is less profit in selling bright colours not associated with a gender, because it is more likely to be reused by subsequent children.
This is a huge influence on people's decision making when it comes to how much they spend on a new baby. I know people who have bought new prams on the basis that the one they currently have is the wrong colour!
So I have a problem with the degree to which we are being manipulated for profit with this. I do think that a lot of people have to comply with these 'rules' due to peer pressure as much as their own preferences. Afterall everyone who makes the assumption of gender based on a child's clothes has bought into this.
Whilst its not unique to the UK, the UK is certainly worse than other European countries for this need to conform.
I think there are a lot of knock on effects further down the line. I don't just think its about gender stereotypes in careers and family roles. I also think its about the wider pressure to conform and fit in within society rather than encouraging individuals and innovation. Thats something that effects both genders and our long term future as a country which has succeeded because of centuries of this creative and free thinking attitude.
So in terms of parents who refuse to dress their daughter in pink, but allow her to grow it long, its not just about gender - its about rampant commercialism.
I have no idea why people feel like they have to find out the gender 'so they can prepare'. A baby does not need commercial products. They do not need a room of their own. I think it just shows up our values as a society obsessed with 'things'.
Its depressing.