Pink and Blue choreographs how women and men are to interact in relationships. It's a way of telling us who to like and who to be with before we can consider someone as an individual. Less importance upon 'pink and blue' broadens the range of relationships available between women and men (including, of course, friendship).
As for romantic relationships, 'pink and blue' is not the singularly appropriate structure for women and men, and in many cases overemphasizing it can ruin relationships. It can be insulting to women to be treated as the weaker, submissive, dependent, lesser counterpart of a relationship. Without even taking it that far, women might just get bored with rigidly masculine partners...
Why do they always have to be the object; why can't the guy be be 'beautiful' also? Ever noticed a girl going for a gay guy? 'If you weren't gay I'd marry you in a second...' Obviously it's not the guy liking guys that she's attracted to, but it might be that guy's freedom from heterosexual male typecasting... maybe it's his freedom to look and dress, or to be "sensitive," without being terrified of threatening his masculinity.
Men and women are changing, lines are blurring, and roles are evolving. Feminist progress frames the changes for women and lacking a comparable movement, men tend to react to the way women are changing more than consciously changing themselves.
'Pink and Blue' operates repressively in male friendships as well by making it clear that there is no 'pink' allowed in the friendship. Good friends inevitably care strongly for each other at some point along the way in the friendship, of course, but this cannot be demonstrated in open/honest ways. It's a precise game, letting a friend know how you feel about him -- an art form really...