I played WoW for an extended period of time, and honestly, their quest system was as much a grind as anything else. It was the best way to get XP, and thus, you were basically forced to quest if you wanted to level quickly. (And honestly, in a graphical MMO*, that's pretty much all I'm out to do. Content BESIDES the grind is usually severely lacking.)
Questing usually involves reading a spew of text from the character. Getting an item to take somewhere, kill some thing, or being asked for certain items. You go do your thing, find that quest character again or find some other random quest character, click all your buttons and voila! You get some XP. This, to me, is way more tedious than simply finding a camp and some friends, pulling the camps until you break it, and moving on to the next. At least then you're dealing with INTERESTING content, other players. When you're running all over the world doing random, dorky quests, you're so busy doing the quest that you barely interact with a lot of players except to hook up because you need to kill the same mobs, kill those mobs, and move on.
Granted, some people like this, but I've NEVER been a big fan of mandatory questing, which is concept that has been around in muds FAR longer than on WoW. True, you can still level by doing the traditional grind on WoW, but that choice is not the optimal way of leveling.
Honestly, I'm not sure that the grind is a bad thing if you have fast leveling and PLENTY of other content that are fun, provide advancement (even if it's not XP or coin), and promote player interaction in a PRODUCTIVE manner. I happen to enjoy the traditional grind because it gives me plenty of time to do other things with my character assuming the game is designed properly.
