Your observations resonate, and the same story about facebook and the VLE seems to have played out across other European countries also. Your thought about student self-organised spaces is, I think, the way we should be thinking. Indeed, the “learning and development” community seems to be getting rather excited about social learning platforms with peer contribution and expert curation of content. I am rather more sceptical about the use of “game mechanics” in the long run. Gamification is no substitute for something being genuinely useful for studying.
I think it may be time to swallow some academic pride and to look to products like http://www.curatr3.com/ for some inspiration on where to go next. This probably means we should slim-down the VLE and accept a more fragmented reality, rather than to imagine some more bolt-ons to try to recapture the facebook activity. And yes, there is a big implcation in all of this for the way people are thinking about learning analytics; VLE activity data is hugely misleading.