Speaking as one of the people BBKat's mentioned that lost out on some creatures when someone was banned, I'm here to do what I do best and be the devil's advocate. what about the players who get a temp ban? Granted, yes, they did something against the rules and therefore are at fault, but when they come back, what if it was enough to straighten them out and they're a model player? If there's a list or even a marked difference in their account's appearance, what's to stop players who never had dealings with the temp banned person from making a huge deal, adding them to their blacklists, and making Magistream unpleasant for them?
Yeah, it's a pain when you have gold/creatures sitting in limbo but I can see this simple suggestion making more work for the very people everyone is saying this will save from more work.