@WTFE Your description of Staff failure to follow up on a player-run plot is, in my experience, a large part of why people stopped running PrPs. However, even when Staffers have shown their willingness to follow up, there's little impetus from players to run them... again, in my experience.
I was actually trying to get to the point of--even when Staff is running active things and dragging plot-hooks galore out in front of the players, very few players can be bothered to follow-up.
All of this points towards a larger problem, however, which @WTFE brought up too. Players have been burned so many times by bad staffers, and staffers have been burned so many times by bad players, that no one trusts each other anymore. Staffers (often) put a layer of bureaucracy between players and the ability to do anything because they don't trust players to be anything but batshit crazy. Players won't put themselves out there because they're afraid of having their stories messed with.
Here's where I disagree with @WTFE on it however--I think that the sense of entitlement is very real. I've seen it staffing games and I've seen it playing games, players who basically hang around until there's a Staff-run plot, then rush toward it, and afterwards bitch about how it wasn't all about them as they go back to idling in the OOC room. A large portion of today's playerbase isn't around to tell stories, they're there to be entertained. By other people (as @saosmash mentioned).
Yes, there are still a good salting of proactive, motivated, engaged, and engaging players looking to tell cooperative stories with others--they're gold. They are what help staff turn a game from a string of encounters into a living story.