It's not that pink is intrinsically bad, but it is such a tiny slice of the rainbow, and, though it may celebrate girlhood in one way, it also repeatedly and firmly fuses girl's identity to appearance.
And isn't that, at it's core, what the princess fantasy is about for all of us? "Princess" is how we tell little girls that they are special, precious. "Princess" is the wish that we could protect them from pain, that they would never know sorrow, that they will live happily ever after ensconces in lace and innocence.