"I don't get why being a princess on the inside is something to admire?"
Well maybe because we can't all be princesses on the outside?
The tall girl, the one with braces and glasses, the chubby one, the one with learning difficulties, the one who lives with a foster family, the black girl, none of them would traditionally be a princess. The qualities of a princess come from inside so it really doesn't matter if the princess is wearing a pretty dress or looks like a hotdog!