There should be two separate story "trees" for the crafters/gatherers and melee/mages alike. Those who choose combat roles should be able to experience the story and the rank quests that are currently existing, while crafters/gatherers should be going on quests relating to internal conspiracies, becoming the top merchant in Eorzea, or some such stuff related to crafting.
The fact that both do the same quests? THAT leads to mediocre content.