I craft, I only use one retainer for the materials, I have six for glamour, and one for housing and materia.

My inventory is fine, I have 40-something slots used from my own personal inventory, and I carry a lot of miscellaneous stuff like fireworks, Sigmascape pages, buff food, potions, etc.

The only points that were valid from OP were:
1) Certain items not in the currency menu (eg. Anemos Crystals, Protean Crystals, etc.)
2) Retainer UI being clunky.

Inventory on its own is fine.