First of all, the problem is with the developers. What do you think happens when a player opens the server list, and finds no one playing? They leave. They go to some other game, where people are actually playing. Because of how antiquated and poorly structured the server design is, even if people are on the servers, chances are, the new player will have to wait in line and/or the players on the servers will refuse to play them. Which leads me to the second problem with Quake - the players.

For whatever self-serving, idiotic reason, Quake players refuse to play with practically anyone. If your ping is a little 'too high', they won't play you. If you weren't selected specifically by them, but you join the server in hopes of playing, they will kick you off (despite the fact it is a public server). It's like, they do everything they can to prevent anyone from actually playing the game. How can there be a game if there are no players?

When people go to the server list, they do so because they want to play. If they didn't have to wait (either in line or just for anyone to show up), they would play... otherwise, to reiterate, they wouldn't have even looked at the server list. But, when they join a server and get kicked off by some incredibly idiotic dickhead, or when they have to wait potentially beyond the amount of free-time they have, or would simply rather spend their free-time playing instead of waiting, of course they will go somewhere else.

People think there is no interest in Quake, but really, it's just basic design flaws the developers fail to correct. The whole community is so egotistical, they think the game is perfect in every way, and eventually, everyone else will realize the game is perfect, and will then gladly waste all their time waiting for games, or getting kicked off public servers for no reason other than the players are self-sabotaging jackasses, or waste their efforts attempting to synch shoutcast (or other third-party entities) with Quake and GTV, or scouring the internet looking for the files they are missing. At least, with the last one, things have been fixed... but all the other flaws, which are in most cases more severe, still exist and have not in any way been addressed or corrected (except in Q4, but, with Quake Live, they reverted back to the old, failed system instead of moving forward and correcting the errors of the new system).

Maybe a solution to waiting times, is to have a single master server per game-type, and for everyone to simply join that server and wait for the system to pair them with opponents. If done correctly, waiting times should be virtually eliminated, and since there is only one server displaying everyone currently playing that gametype, the servers would always have activity.

A solution to synching third-party entities, is to have plugins, that anyone can create, in order to perfectly and easily synch their organization with the world of Quake (maybe it's something like having a clanbase tab next to the 'play online' tab). That way, the system is still open to third-parties, which might be superior to first-parties, and the various other advantages of allowing and having third-parties also still exist, but without all the flaws.

As far as players sabotaging themselves, I don't know exactly what the causes are. Maybe they rocket-jump too much? In a game, where the objective is to kill the other players... you'd think the natural result is that the number of players would continue to decline. But obviously, that kind of thing can only lead to one result - the death of the game itself. If all the players are dead, so is the game. Maybe there is only one solution, and that is to change the primary objective of killing into something else... something more creative possibly. If though, people want to continue trying to make deathmatch work, which has been all but killed by the players who are so good at their jobs of killing everything (including themselves), maybe you can just stop the players from kicking people off servers, or doing anything else that might decrease the amount of players (on or off servers)?