The problem is simply that the majority of online players have either grown tired of the same old footsoldier deathmatch and CTF combat and play larger scale games which incorporate vehicles
You just described Tribes and Tribes 2. The best darkhorse "large scale" mulitplayer CTF game, even to this day.
I think the problem in the gaming industry is that most console gamers or those new to the PC realm of games judge games based on the single player game and the cool graphics.
Us old school folks that remember paying 5$ to play DOOM on an IPX LAN at the local radio shack, things like Action Quake and when the internet was still called the information superhighway judge our games based on the mulitplayer gameplay, movement, physics, netcode etc.
Dont get me wrong, cool graphics are nice, but not to the point where it kills the intense gameplay found in classic games like Q2 or Tribes. If you Quake fans are hurting over Quake 4, you now know what the Tribes community felt like when Vivendi made Tribes Vengeance.
Q4 doesnt quite have that same magic for me as Q2, but it looks pretty and has some new things. Quakewars should be interesting. Right now the gaming publishers have a very general market audience which is pretty generic. We need some new kind of game publishers made up of devs and veterans of the industry to make and market high end games to the extreme multiplayer fan, and the Vivendi's and EA's of the world can market and make their mush for the general console market.