They way how the Materia System is right now, it should be removed from the game and the stats we get from them should be baselined.

Its an endless hunt for higher tiered versions of the same crap just to get a few stat points more, which in themself don't matter at all
As if you'd feel a difference at the begin of the game with any tier 1 to 5 materia, first from 6 onwards the stat boosts became good enough that you can see a little difference, compared to having no materias, due to stats having cap milestones where any stats between two cap milestones are effectively wasted.

The best Materia System FF14 should get is the same one, from which the whole system originated from FF7

Materias should have not tiers, they should have just 5 evolution levels to master their abilities they can provide, and if you mastered one materia, then you gain the same materia again in its beginning first evolution form.
Materias shouldn't provide Stats, but class based Buffs and Skill Upgrades to improve for example for increased MP Cost the potency of spells (MP Turbo Effect from FF7)

Materia that gives boosts to HP or MP for the cost of reducing an other Stat, like for example Determination, Crit or Direct Hit, if you prefer more survivability over offense for example to customize that way your character more.

There could be a materia that can maybe increase the range of skills, or increase the number of target/hits, or one which increases your movement speed baseline to Sprint Speed, if equipped.
There would be so much more fun, if Materia would be reworked to a system that actually does something for character customization and supports it, instand of keeping this endless grindfest for lousy tiny stat increases.

Weapons, Upper Body n Lower Body have maximum 4 Slots, when rare, 5 when modificated/ total max 15
Head, Belt, Arms, Legs have 3 Slots max, 4 when modificated. Total max 20
Accessoires have 2 Slots maximum, 3 if modificated, old content gear of lower ILvl than 460 gets reworked to this then. Total Max 15
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Grand Total Max if everything got modificated to upgraded version > 50 Slots of Materia that players could use then to modify n customize thei characters.

Way more fun, than hunting for Materia IX next, just to see having some Stats a few points more, that are eventually wasted becaus the Stat doesn't reach a next cap point where the effect of the stat increeases for you, or the effect increase is so low, that you see no difference.._ If a skill recharges now in 2,35 or 2,38 seconds, plays no role, our eyes will see in combat NEVER a difference under such microscopic number changes!!