Let me extend this.
As someone who just rolled another char on a different server outta sheer boredom, the msq is mind numbingly boring and monotonous as all get out. Not to mention the fetch quests, and more fetch quests and yes even more fetch quests.
But you go back and reroll a char on XI and the story still holds up. Its still exciting to re-experience. The world....feels alive and truly in danger. Sure it can be long winded in parts but damn does it tell a good story overall. From the expac main quests, to the mini expacs and the little side stories you come across. You don't just bust through them to get them done. You experience them.