In my experiences (I'm a person who's been in the Reaction Q3 community for about a year, and been watching Quake 3 grow since its release), I think the main fact is that Quake 3 is disliked, not very popular. And those who DO play it play one or more of these things -
Quake 3 Vanilla (regular baseq3, that is)
OSP
Urban Terror
and
Rocket Arena.
Oh, and a good dosage of Q3F.
I think the main thing is that not enough people struck the pot soon enough when Q3 was released, didn't get people hooked on it (lots of promise, but the first "big" release didn't happen til' what, June 2000?
). And another thing is that most of the mods for Quake 3...well...they aren't very good. The speed is so slow it's fucking crippling (pardon my language) in most of them. NSQ3 is slow as hell. Q3TC is real slow. UT is slow too. The fact is, people kept doing too many "REALISTIC" mods that focused more on realism and balance rather than - FUN.
Mods like Reaction Q3 and Western Q3 are FUN mods. They have a very fun feel to each of them, and they're good to play. But the problem is there's
1. Not enough server support
2. Not enough players - and the not-enough-players thing is a horrible loop because nobody tries to play because nobody's playing, thereby making it so THEY don't play, then people don't play because THEY don't play....err...you get my point, right?
and
3. The Punkbuster/CD Key stuff, which has caused many to stop playing due to warezing Q3. (RQ3 really REALLY died after 1.32 was released)
I think it's not so much the lack of support from news, publicity, etc....it's just that I don't think people like Q3 a helluva lot. Not to mention there's so many damn choices, the whole factor of PC hardware, and the main definitive mods (Urban Terror, OSP, RA3, Q3F, etc.) suck up most of the players. Plus, like I said, the CD key stuff pisses people off since so many internet idiots (80% of the internet public, IMHO), don't wanna pay for nuttin'. CHEAP BASTARDS.
Quake 3 is a sad thing. GREAT game (baseq3, for me, is DM perfectted), has some GREAT mods (this mod rocks, RQ3 rocks, etc.), and some amazing maps and a good engine...but it's like....nobody cares.
I wish more people would play Q3 and the cool mods like RQ3 and WQ3 but...that won't help any. The best I can do, and I think the best we can do, is just play it as much as possible. Maybe us here can organize weekly games for us all to play, getting people interested. Doing it once a week, ritualistically, is one way to get to playing it more.
Anyways...yeah...tis a sad thing.