I was wondering about this too, mainly as I had to shop for a girl's birthday and wanted to get her some clothes. Also went in for a birthday card and the majority of the cards aimed at women and girls seem to be pink too.
Back in the seventies I too had short hair as we swam a lot and it was practical, so did many girls. I lived in trousers as did many girls or shorts in summer and I can't actually think of any stuff I had that was pink, lots of primary colours etc, comfy and practical, lots of jeans.
I really remember the pastel shades becoming a thing in the 80's and even then it wasn't wall to wall. Now it's everywhere, even women's sportswear you get loads of pink etc, I find it hard to get trainers because I want black ones and you are assumed to want mens if you want black.
I do suspect it is linked to money and the making of. It largely always is and I think you're right Stilletos the disposable nature of just about everything is a factor. Not something that's very good for the environment though!