I would suggest that the more accurate reason why people aren't migrating their files from the old vault to the new one is because they are no longer part of the community. They have moved on, hence the initial run of volunteers mining old projects and migrating them instead.
I don't know if bittorrent would be a viable solution; it has this pesky necessity of someone having the data readily available at any one time and an even more pesky likelihood to eventually die out with decreasing demand for content. Demand for NWN content really doesn't have the demand necessary to start off with.
I'm not sure an abandon all hope ye who enter here outlook is productive but, as another old saying goes, nothing comes for free. I would think having a central option and discussions toward a more stable solution is paramount, and I would also think that a little vault access issue is probably a lot better than having to hunt down a myriad of dropbox or other "cloud" services- some of which are even less permanent unless every person were to invest in premium accounts and are already on shaky ground when you consider certain similar services subjected to government take downs, causing people to loose access to all their files, the irony being some government employees having lost theirs as well.
If one were to champion a move to drop it and kill all investment and support, the question remains: what then?
IGN is questionable at best and on borrowed time at worst. Nexus doesn't seem to be a viable or popular option. Gamefront is horrendous and Filefront isn't far behind IGN and extremely buggy the past year. So what then? Hit each other up by PM when we need a file?
Rolo took something on himself as an attempted solution to a dilemma and, were I in a more comfortable financial place, I'd be glad to contribute. As it is, I'm not, but I'm not resorting to "give up, dude" either.