I have always maintained the +event system, widely used for plot scenes since TR, is at least partly to blame.
More often than not, you sign up for an +event and when you show up, you end up with a group of random people that you may or may not know. Everyone has to go out of their way to explain why their are there, Typically, the reasons are a stretch from what characters usually do. Right off the bat, +Events don't fit in with most characters' normal routine, and they immediately become a side story.... a MU*s version of a one-night-stand. There is usually very little personal stake for the participants, and little incentive for them to follow up on clues, because they don't fit in their personal stories.
Granted, using +event for scheduling purposes makes things easier. +Events are well-suited to certain types of scenes, such as one-off "Monster-of-the-Week" scenes, or game-wide major plot scenes. For ongoing mini-plots and story lines, I think using +Events will only end up with frustrations for the ST.
The better option is to drop plot hooks for the more active players, those players who are known to share information with others. Ideally, give them a personal stake in the plot. Drop the hook in @mail works, but even better is introducing it unexpectedly in RP. Doing it this way makes the plot personal to the player, and they are more likely to respond positively.
I have done this to good effect in the past, but I'm choosing not to address the downsides to this arrangement; one example that comes to mind is how whiners will claim staff favoritism if they feel they're not getting enough personal attention. Also this method will likely not work very well for large games, but these days most MU*s are on the smaller side, aren't they?
