That is the one major gripe I have with the game as well. You get max bis gear, but there is nothing to do with it. Looking at games like Everquest, there were alternate advancement levels to grind out, where you'd unlock an additional point each time you hit a full exp bar at max level which you could spend on improving stats or even unlocking new abilities. So getting raid gear was awesome because it made the exp grind on non-raid days so much more efficient, so you felt like you got something out of it since you were still constantly improving your character.

I can spend 1-2 weeks farming mounts, minions, cards, but ultimately that's just fluff that doesn't really matter, so I usually end up unsubbing till the next content patch comes around. That's just the way the game is designed.