I really want to replay the story, like, a lot. I'm unfortunately discouraged to do so, because why sink hours to replay the story when I could be grinding a job/raid/relic/etc with all that time and actually get rewarded for it?
The incentive for clearing the story for the first time is obvious - it unlocks side content and dispense enough EXP to reach cap. Obviously, NG+ shouldn't do either of those things. NG+ unlocking raids and such is nonsensical at best, and it giving large doses of EXP would probably greatly harm the current leveling grind ecosystem.
What NG+shouldcould offer are exclusive collectibles with no gameplay impact whatsoever. Stuff like mounts, minions, titles and glamours. It shouldn't ever be something that would give you an advantage over others, just something that make you see a player and go "wow, this guy did the MSQ again and got this sweet thing? I want it too!". It could even be simple variants reskins or recolors of existing toys, like a pimped out Manacutter or a glowing chocobo chick minion (that last one sounds boring but you get the idea). It would've been cool to be able to get the main cast's outfits from NG+ as well but that will not happen due to reasons
Instead of awarding specific rewards with specific story-lines, I imagined a system similar to Achievement Certificates, where you'd get tokens by playing quests again to spend at a merchant in whatever is the current highest level zone. Maybe a dev self-insert NPC?
Of course such a system would need proper balancing as well as to prevent players from replaying the same 2-3 quests because they're short and easy.
I hope I didn't treat the story as a chore because it is genuinely amongst if not my #1 all time favorite stories in any media. It's simply that it's very lengthy to replay without incentive. I try satisfying my replay craving by listening to the godly soundtrack but it makes it worse, and watching other people go through the game on Youtube or on streams just isn't the same, because it's not your own Warrior of Light.
I really hope this reaches some dev's attention. This game is absolutely majestic and I can't wait to see what's next!