For me, open world content makes an MMO feel alive after max level. Otherwise, MMOs that focus entirely on dungeons past max level start to feel like a Diablo style lobby-game setup. I go wherever I need to in order put together my group, either get teleported to the dungeon or run to its doorstep, but otherwise have absolutely no reason to go anywhere or do anything.

I've seen open world content done right; Square just hasn't gotten that down yet. But they will.