The problem with arena shooters is that they always focus on free for all. Free for all is boring, so is TDM for the most part.
What is run is playing round based game modes(with no respawns), hence clan arena in Quake Live is by far the most popular gametype. Decent enough mix of strategy and fun. It's not mindless like the other game modes.
Duel is also good for this, but the problem with duel is that it is extremely punishing for newer players. It's just that the learning curve is very large so a lot less people play this.
JigglyWiggly_'s comments