On a RP server, I understand judging and accepted/denying people based off their username. It's not understandable on a PvP/PvE server. Quite frankly, on a non-RP server, it's absolutely ridiculous to care about someone's (non-offensive) name. Just because their name isn't something that you care for doesn't mean you can't play with that person.
I completely understand the importance of names on an RP server and and I believe immersion in that context should be respected.
However, I don't really care too much on the PVP server I'm on. If the name is offensive, however, I won't group with that person, and will probably put him or her on ignore. If the name is some typical juvenile idiocy, ditto, especially if I notice a lot of accompanying spacebar jumping spasticity.