I don't know whether the world was less pink 30 years ago as I [admitting my age] don't go back quite that far. What I DO remember from early childhood was being told when I expressed interest in being a biologist that I should want to be a ballerina and being given a barbie doll by every well-meaning-but-obtuse relative at each and every gift-giving occasion.
It didn't stop me from being very contrary and insisting that my favorite color was, in fact GREEN (it was really blue, but my 5-year-old self didn't want to admit this as everyone else liked blue as well), and disassembling barbie dolls to see how they fit together. I still ended up in IT with all the boys.
Gender roles are certainly fluid, and saying "girls wear pink" may contribute to crystalizing gender roles, but I think it may be worse to, even subconciously, say "girls do x and boys do y and I don't want to be a girly-girl so I do y" in that it reinforces that some activites are for girls and others for boys. Even though it encourages girls to cross a percieved gender barrier, it also tells them that there IS a gender barrier.
FWIW, Asda is owned by Wal-mart, but seems to take stocking suggestions from Tesco as I have bought the most adorable, girly, brown/blue/green/purple/red/gray outfits from Wal-mart and haven't seen anything similar at any of the large chains. No, not even Mothercare or Pumpkin Patch, although I will admit that those girls' sections are slightly less pink-washed.
**will let my daughter help me weld on my car grill AND teach her to waltz, for no other reason than it seems to confuse people when you can do both.