While I agree that not every crafting (desynth) class needs to be able to make all of the useful things, we're currently operating in a market with about 3 useful things to go around: Mastercraft demimateria, fieldcraft demimateria III, and battlecraft demimateria III. The access to said materials isn't very even and GSM can pretty easily make all of them. It made a bit more sense when primal demimaterias were more relevant (if they can even be said to have been relevant) since the spread on those seems to have been more thought out.

I hesitate to say we need more necessary items from desynth because it's not really a part of the market I enjoy, but the current state of things is very off balance.