Ahh shit man. My daughter calls herself a princess. She can also put up shelves, throw a ball, and is top of her grade in the martial arts she elected to do (although this is probably because she saw me head off to do them, so my bad there yes?). We have always spoken to her like she is a human being, and part of our family - and you know what? She's pretty damned independent and capable. You can call her princess without applying the don't do anything to them. Also, fuck it. If she wants to find a prince and marry the man, why the fuck would I stop her.
I don't know why we can't just let kids be kids. If a boy wants to call himself princess, nothing wrong with that, but as soon as a girl calls herself princess we're all up in arms.