Solution to crafting problem: Make the best gear drop from dungeons. And let us meld materia to it.

This would not only make a need for crafters to meld the materia, but it would also mean that the not-best-gear-but-still-crafted-gear would shoot up in demand as everyone started to spiritbond to create materia to add to their gear.

All the while, the players will still need to complete endgame dungeons in order to have the best gear. They'll just need a crafter to maximise it, and a crafter to create the goods that you spirtbond in order to maximise it. But until they obtain that insanely-hard-to-get-gear, they'll still be unable to "buy to win".