MMOGs generally have very little "interest" amongst the public at GameBanshee, the reason for this being that such games due to their nature generally spread their activity out of a few (official/semi-official) forums, as compared to ordinary singleplayer or multiplayer games which are spead out over many forums.
I don't think there would be much usage if a GuildWars forum was created, and I'd say that for now the Generel MMORPG forum could handle that. If the need arises then it could be introduced.
But of course ... it is up to Buck Satan such decisions