Well, it could certainly work a lot better. It's not successful because they have a super great formula. It's successful because it's either this or Garrisons, and pretty much everyone said a big old FU to Garrisons a months after release. Right now SE is using a formula created by another company, and they are riding the experience of a brand new expansion and the fatigue of another game's missteps. It doesn't hurt that it's probably the most beautiful MMO on the market, but make no mistake - Blizzard knows they are in trouble and need a big win. The competition isn't over. SE can't just hum along with this content model and expect to be successful forever, especially if core FF fans are already tired of fighting the same Primal\dungeons on different tiers ad naseum.