As someone who's played far too many MMO games for his own good, I've seen lots of great ideas, and even more terrible ones.
While many of us played the Alpha Version this past December, we've probably seen more than our fair share of quests. I personally wasn't all that impressed with what the team's done, although, I do think that it was an improvement compared to its 2010 counterpart. This raises the question; What can Square-Enix do to improve quest-based leveling?
There are two main factors that detract from the overall experience of questing; relevance and running back and forth. The Final Fantasy series has always been known for its narrative; no matter how bad the gameplay gets, people tend to play them through if the story is good enough. If 14 has such rich lore, building compelling quests based around completing heroic deeds should be cake. And while they're at it, have quests send you to new quest hubs naturally, rather than sending you there only after you've completed all the quests at one particular hub.
By no means is this an original idea, I've just been playing lots of WoW since 14's been down, and I really think that Blizzard has improved questing in Mists of Pandaria. At very few points did questing feel tedious, and more often than not, I was interesting in finding out what happened next in the quest line.