Oh, it was pretty easy to die in Quake 1, too, if the other guy has the RL...
In UT2004 the flag carrier can shoot, but if you're playing Bombing Run or use a mutator that suddently stops. Want a two gun limit? There's probably a mutator for that. Want a slower pace? Lots of mutators for that, too. Mutators are fun, especially the RPG mutator.
Besides, we're leaving Onslaught out of the equation. Onslaught involves tactics, combined arms, etc. It's more a capture point gameplay instead of "run into their base and get the hell back" and a lot more dynamic than standard CTF since the frontline is moving. I think some people who played Tribes will now argue that Tribes had more strategy than both Halo and UT2004...
Also, the strategic gameplay reminds me of how CS is meant to be played. No run and gun, you can't run when under fire and a few shots can down you, plus you are out for the round if you die. Personally I don't like it, but hey, apparently enough people do.
So basically we could argue Counterstrike vs. Halo...
EDIT: BTW, Bill, which Virus game are you talking about? There's more than one, I have a Descent-style RTS of that name.