Right now it seems Books is where the party is at. Even at wotmania when the quizzes used to ask why people came here, the answers were overwhelmingly for WOT. And now we have failed to attract people who may have come for the last book and stayed to discover Scott Lynch in Books or the community here. All because of a ghetto.
Oh, it all predates that by years. There was no hope whatsoever to "attract people" for WOT for AMOL, and it's been a long while since Wotmania/RAFO has been a place to "come for WOT and discover other writers".
In fact the WOT MB that was the locomotive of the site has lost its momentum in between the release of COT/KOD. One reason is that at Wotmania the "COT bashing" was never very well contained and it tainted nearly all the threads, which ended up annoying those who liked the book or wanted to get over their disappointment and discuss other things. We lost a whole lot of good posters over that, who visited and finally adopted other WOT communities where it was kept a bit more under control. We lost another batch of people when Wotmania gained a partially deserved reputation as a MB with a ton of flame wars over hated characters and little else of substance. Again, the other WOT MBs have tried harder to contain those things to single threads, forbidding Faile or Egwene-bashing in other threads.
Another reason is that at Wotmania the CMB had become the strongest section, and people who often had given up on WOT remained around at CMB with occasional visits to bash WOT on the WMB. That gave the site a reputation for being a bit unfriendly to hardcore WOT fans (that was certainly the only one where mentioning WOT on another MB than the WOTMB could get you flamed....) That explains some of the losses of membership, who went to Dragonmount or Theoryland . We lost more people over the reception of COT itself, however - a whole lot didn't remain around for years just to bash a series they no longer liked, they just moved on.
Another reason, more important I think, is that Mike lost interest in WOT and Wotmania as a result missed out on all the "new developments" that took place around that time, with Tor involving itself more with the WOT fans and Robert Jordan as well. That also lead many members that came mostly for WOT to go to Dragonmount or TL where the "good stuff" was happening, moaning that Wotmania no longer got anything. Wotmania became a site a bit for losers. New fans of WOT were still coming but most didn't stay very long.
Jordan's death marked another big decrease in activity (everywhere, though it was the worst at RAFO). The new RAFO WOT board was presented as virtually a charity to the old members until the series was over, and that certainly didn't help either (it even convinced several old timers incl. the admins to go seek greener pastures). By then most of the WOT traffic was on other WOT sites anyway, with little to induce new people to stay at RAFO if they happened upon it. Wotmania had been in decline, RAFO never was taken for a real WOT site by the WOT fanbase. It was seen as a social site of mostly ex-WOT fans, which it pretty much was.
So basically for many years Wotmania hadn't encouraged much new membership while the other WOT sites have been very proactive (especially Dragonmount), with their webmasters more and more closely involved with the publisher of WOT and the people around the series (Jordan, then Team Jordan).
The OF board did try, but never got a critical mass to really kick things off, and beside all the other WOT sites that also had "other fiction" MBs too, there was growing competition from sites like Westeros and the Malazan Empire where they also have MBs devoted to discussion of other fantasy/SF works.. and much more traffic.
There was never any chance to attract people for the last three WOT books, Dragonmount and TL had the momentum, and all that remained at RAFO were old timers who didn't want to become newbies elsewhere when there was (originally) just maybe 2 years left.
Traffic to WOT boards in general had decreased after TGS, and again after TOM - with less and less to discuss, and the fanbase split over Sanderson as well. There was a big surge of activity before AMOL (to which RAFO didn't partake) but virtually all activities has happened at Dragonmount once the book came out, and what's left happens mostly there (with TL a bit, but it's quieted down everywhere, as on any MB devoted to finished book series).