Hair is just meant to warm your head and face.. That's why it grows back after you cut it, yet if you're in a warm climate, it doesn't hurt to cut. It's kind of nature's way to say that if you're living in a desert climate, you could use a rock to chop off some of your hair or something, IMO.
I had dreadlocks, and now I have a mohawk (previously trihawk before dreads). I haven't noticed I difference in my personality, either.