In answer to the question, "Why have long hair, then?", I'll tell you the answer, at least for my DD10: When she was 4, she decided she wanted to grow her hair to her knees and then donate. She was inspired by the fact that she has gorgeous thick, blonde hair that total strangers would constantly comment on. She wanted to share her "gift". How could I argue? Fast forward 6 years, her hair is "there", but now she doesn't want to cut it yet. I keep thinking she will when puberty hits and we have to wash it more often. Frankly, she has so much hair, it overwhelms her pretty face. Also, as a mom, I worry about too much of her identity being "the girl with the hair", when she has many other fine qualities. But, it's her hair, I don't want to force her to cut it, she never complains about my fixing it for her. So, here we are.
I hope that explaination makes sense to you--I know you weren't trying to make trouble, I thought you might like to hear the logic behind it (in our house, anyway).