There may still be a game balancing issue though. Like if they change classes to balance PvP that would affect not only the PvP servers but the rest of the servers that are non-PvP too, because they would have to keep all the classes the same across all servers. They couldn't have some abilities and stuff different on the PvP only servers.
I'm not against PvP on PvP only servers, but it will affect us non PvP players if they change classes to balance PvP.