Ban them? Yeah, good luck with that. I think people who play an MMO but can't handle slightly annoying interaction with other players should be forced to use private groups.
And the worst thing is, a lot of the people who complain about Open are really only complaining about the possibility of being griefed. They're in every mmo, a bunch of non-victims terrified of being victims.
And what's the worst that happens? They get blown up and suffer virtually no loss.