I can honestly see myself never bothering with this if there isn't at least some xp reward (don't care if there's no gil or anything else you can get). You can't really use it to "play the story as a different job" if you're not gaining xp by doing it, you'll still have to do other things to level the other job so you can keep up with the increasing level requirements of the quests, even more so than usual if you're gaining no xp from replaying the story. I don't really care about replaying through things I've already done for nothing, especially when all I really care about are the cutscenes that I can watch any time at the inn.