Everquest has been the leading online MMORPG for quite a long time. It's only reasonable that it be one of the first supported Online MMORPG games!
There are thousands upon thousands of users logged in for every minute of the day. Each one of these users have probably never dreamed of converting to Linux for fear that their "addiction" would not be satisfied if they did.
I think that the gaming genre could be swayed to convert to Linux much faster if we got these games into the "supported" light!