The only reason I sub is because it is a FF game, I am a FF fanboi and atm I don't see any better alternatives. There is more to come is what keeps me atm because this vibrant world you talk about in OP is certainly true except there is no reason to see it when you are lvl 50. You can talk all you want about leveling different classes or w/e, but I already have the ones I want at 50 with all needed crossclass abilities and while the world is pretty and vivid and alive, it has no use atm (unless I enjoy going to FATEs like Behemoth and Odin which are boring zergfests that completely destroy the coolness of the actual mobs with no decent reward). So the hope of them making use of the world and adding some fun things to do outside of farming instances is what keeps me. Probably on and off until EQN or Titan.