They should do what they did in final fantasy 11. The focus should be on story, missions, and forming parties to reach a goal. The reward may be the opportunity to explore a new land, viewing a cool cutscene that had meaning or impact on the trial you went through! That new weapon/armor or item should be the last thing to expect from a reward.

Although at this point I dunno if that would work. Most ppl would be shocked if all of sudden you don't get anything out of completing every single quest or mission.