I think part of the issue is the number of descent racing
games out there are splitting up the potential field of online
players.
Another issue is that as racing sims get more accurate, there will
be little difference in the "feel" of the various games. The differences
will be which cars and tracks are available, and the extra features
like graphics, sounds, AI behavior, replays, career mode, ... .
For example, by the time LFS S3 is released, it probably won't seem
significantly different than other racing sims released by that time.
The last issue I can think of right now is that the newness of
online *** in general is gone, so there is just less interest.
NR2003 online 300 (weekdays) to 500 (weekends) players online, 90% of
them racing super speedways, the no skill required tracks, which is
why they are probably so popular. (OK, so you do need to learn how
to avoid wrecks and pit well).
GTP mod for NR2003 - a few Eurpoean leagues for this one, but I'm
in the USA (wrong time zone).
GPL - I never saw that many players on VROC, but I probably discovered
out about GPL too late.
GTR / GTL - I expect these games like most others, to be popular
for a few months after release, and then for interest to wane.
LFS - an unusually loyal fan base. Haven't played online in quite a while
so I can't state how many players are actively online.
F1C99-02 - Another game I like, but rarely played online, so I don't
know how popular it was. Just like the real thing, I would imagine
passing would be difficult.
Rally sims - I've never seen or played RBR. I do have Collin McRae
Rally 2005, but only played it a few times. Just can't get motivated
with rally style driving.
Non-sim racing games, for example, NFS Underground 2. 1000 players on
the first night of the demo, but the released game split up US and
EU servers, and not there's maybe 50 players at most on the US server.
Like many players, I spend most of my *** time offline as opposed
to online. I think most GPL players probably fit into this category,
hot lapping for a GPL rank as opposed to online racing. My guess
is that most active NR2003 players are online. With the rest of
the racing sims, it's somewhere between the GPL and NR2003 extremes.