On our raid, I'd say we've lost about 20 people from our raid force over the last months - due to quitting the game. Were those diehard players that'll never leave, too?
Everybody knows that Funcom won't suddenly publish dozens of new dungeons / quests zone, and that we're more or less on "hold" status. One may be okay with that. The game won't draw in hundreds of thousands of new players, and that is something we have to live with.
But the things that actually were made worse, from the small but really, really annoying rez bug to options not saving any more, actively drive people away. Also, of course, marketing stunts like selling "cursed" necklaces and unpolished (and really, really boring) content don't really help, either. Those things are the ones that should be avoided at all cost.
If all you can do will make matters worse, than just do nothing. It's hard, but Funcom apparently has other unsuccesful (but more loved) ventures they can keep their people busy with.