I keep it a bit longer because then you don't have to pay for expensive haircuts if it grows quickly. I also find it easy to just gather and twist it and clip it onto the back of my head out of the way. If I am going out, especially if its windy, I just gather it all up and shove it under a hat.
In summer, I gather it up to keep cool, in winter, if its really cold, I let it drop to keep me warm. Hair is practical and useful in these ways.
I used to have very pretty hair and many seemed to wish they had it because it was a pretty colour and thick and shiny, though I didn't much care for it mostly and would often have it cut very short much to every ones shock an horror and to the secret pleasure of jealous people. Silly people.