Glamour, we already have a system for it, why not use it?

[Mikki]

They could. But it would be a slap in the face to crafters (and gatherers)... there's already little incentive to buy things from us. The few things we can make that people actually want tend to get so much competition that the prices are driven into the ground. Prisms provide a modest yet very reliable and constant income, even to those who are not yet max level. It also adds some value to beast tribes as they sell items used for prisms (which can also act as a gil sink if they don't want to gather the items themselves).