Well for one thing, the lvl 90 quests don't give exp currently. Postgame quests only give EXP starting when the next expansion comes out and they aren't cap level anymore. And it would be a bit of a niche thing, since if you start a current expansion at the earliest possible level, you should hit max level exactly when you are expected to. You often need to even grind a bit, though they've been trying to balance the leveling experience to avoid that as of late.

Also they probably won't add extra gil-gaining methods to the game since they are currently doing what they can to remove gil from the ecosystem.