This would, in turn, lead to more players choosing to purchase gil, creating a vicious cycle that would feed further RMT abuse.
How about a simple solution: Introduce top item level, craftable gear that requires Coil drops and is Bind on Pickup, i.e. only usable by the crafter himself?
It wouldn't hurt the balance in any way, but it would give a LOT of incentive to level crafters, especially since Allagan/Mythology gear cannot be dyed/customized in any way.
Simple, no?