When they re-adjust the level balance so it takes a year to level 1-60 instead of 8hrs, and they take away the dungeon finder tool, so you have to actually make a Scarlet monastery run from South Shore (as alliance) ill "think" about coming back. And get rid of gear score, hide the stats from the players, stop third party plugins and make Molten Core a challenge again !!! (heck i remember grinding black rock depths for three months before we cleared it) Outlands is a empty wasteland because people spend as little time there as they can as they pass through on the dungeon queue fueled grind to the level cap.
Wow, getting less and less enjoyable with each expansion, i don't know why they don't just get rid of the content except for the major cities, pvp zones and raids, no one bothers with the rest of the content except on the race to level cap.