I know this is a touchy topic with many complaints.  I'd like to add my voice with a quick analogy:

Let's say you open a restaurant when you're young and stupid.  You call it "Eat at Joe's."  Years later, you become more classy and prefer to be called "Club J."  It's the SAME location, SAME cook, SAME menu, everything is the SAME.  If you have a criminal record from "Eat at Joe's," it follows you to "Club J;" the ONLY F-ING DIFFERENCE is the name of the sign on the front.  This is essentially an aesthetic or branding change, NOT a substantive change and NOT a historical change.  

I fail to understand YouTube's reluctance to allow changes to your front sign.  We need a solution to changing usernames that allows you to re-brand yourself without changes to security or rules history--other sites have allowed this successfully.  

YouTube: please allow changes to usernames--this is a critical aesthetic of our online identity.  We appreciate YouTube and we're grateful for it, but being called by the name we choose is an INDIVIDUAL freedom in any forum.