When I was small, I had a fabulous pirate's chest that my father had built for the four of us children. It was filled with all sorts of to me, then weird, old fabulous clothes like parts of my father's wedding tuxedo. The best of all were my mother's prom dresses. One was my special favorite. It was huge and fluffy and pink with sequins sprinkled all over. I would put it on and pretend to be Glinda. I'd turn my brothers into flying monkeys.
Our clothes just don't let you be Glinda! In playing with kids and talking to their moms about this "Princess Obsession" that they frequently found so unsettling, I'd mention my escapades as Glinda and ask them if their wardrobes, at least the portions of them they'd be willing to turn over to their kids were much fun. Almost unanimously, they'd regretfully say no, they weren't.
I think this is a large part behind the princess phenomenon. Children have not really changed as much as we may think, but we have.