I'd love this. Let us redo the MSQ, class/job quests, and sidestory quests.
It's not the same as starting a new character because it would be possible to just continue from one quest to the next, giving us the story all together. This is especially an issue for the class and job quests that come only one quest each five levels. Every time I go back to a class/job I haven't played for a while and level it a bit more, I end up with the next page of a story I'd left off on weeks or months ago. The class and job questlines have some good stories to them if you can actually remember what had been going on in the previous one. I'd love to go back, once I've completed a class to 30 or job to 50 or 60, and review the whole sequence of class/job quests in order, putting the story together so I can see it all at once. The Unending Journey only gives a few little bits and pieces here and there. The majority of what goes on in quests happens during non-cutscene dialog, and that's currently a one-time only thing we can't get again except with a new character.
And what about high-level side stories. There are likely a lot of people who would enjoy doing the Hildebrand quests again, but wouldn't want to start a new character and level/gear them all the way to 50 just to get one more run through that sidestory. The effort to payoff ratio just doesn't fit.
Lore junkies would likely love a feature like this, too. How many "didn't that one quest back at level X mention something about this?" questions could be answered if you could just go back and repeat the quests that relate to whichever issue you're looking into.
