Good point Fugazi. What I'm suggesting is moving the warning 1 page into the registration (directly above where they type in their desired name). I don't know about you, but my eyes glaze over when I see a huge list of Terms & Conditions. I just auto check the "I Accept" button without reading.
Here's the location that should be more effective:
With that said, I believe users
should be banned if they drag their feet or give you attitude about changing their T-I username. Especially if there's a warning on the registration page itself. Actually, I'd be willing to agree to an immediate ban after we update the registration page.