I think for materia crafting to work properly the entire materia system would need to be adjusted. Keep the tiers, but would probably want to add in HQ results -- sort of like they had in 1.0 (where different tiers of materia would allow for a range of stats). It might seem a bit weird to have a materia centric class and allow all other crafting classes to infuse materia as well, but perhaps a small benefit like being able to infuse materia into any type of weapon or armor would suffice. It would certainly be a popular option for people who dislike crafting typically but want to use materia. I would like to see them actually be better at melding... I'm not sure that would really upset any balance since to be very good at crafting currently you really need to level up all crafters, so it's not like it would change the dynamic in that respect.

Enchanter feels too much like what materia already does (or really, what I'd like it to do) to me. Maybe there's room for both, but ideally I'd like to see them combined. If one could use materia on raid gear, and materia existed to enhance abilites/ traits as well as stats, I'm not sure what the difference would or should be. I think the answer should be more and more interesting materia from a materia crafting class to do any sort of gear enhancements.

I agree that alchemy needs a buff. I'd imagine that the vast majority of people who leveled the class did so only for tricks of the trade and comfort zone (and to have all crafters at 50). They make so few things that people find useful, and even those few things are often weapons. There are just so many problems with medicines in this game, it feels as if the game was built around the idea that you'd never need them and to reinforce that notion they were made to be fairly weak. I feel like it would be very difficult to balance the addition of useful medicines with current battles. Perhaps as an interim measure they could make stat enhancing medicines work more like food (weaker potency over a long duration). Then at least people would use them and you could accurately predict that behavior (eg. DPS will always be using STR potions in raids). It would give alchemists something of a purpose while smarter people than myself figure out something more imaginative to do with that problem.