When I first set these forums up, i had no name requirement. At some point it became a requirement. We gray out the names that don't meet our naming requirements. Some of the accounts are abandoned and they have a message waiting for them if they log in again. Other accounts are more like "if you don't like my creative name, you can close my account."
As with many things, the grayed out name feature came about because of reasons. We were getting a lot of people looking at old accounts or locked accounts and saying "if they get to have a creative name, why can't i have a creative name?" It turns out that the grayed out name thing seriously helps make less work for us.