A new store opens up that sells some of the best stuff in the game, plus you can buy tabs that perm increase strength, stamina, wisdom or dexterity for 5000 a pop. Plus you can buy your own house, fill it with furniture and grow your own herbs/crops to make hp and mp refilling items for free! How is that for a final reward?
Also, there is a new game plus, I'm debating if you should have to continue to buy into this town's future each playthrough or if it shouldn't reset from game to game and the current town status carries over to the next game. So if your fook it up your first time and the town dies on you, you are permanently closing off this goodness.