It should be a permeate thing because you end up wasting so many styles that can go on other characters. Restore it to how it was before, when all characters shared the cash shop inventory.
You should at least be able to by Nodestones from npc's, like 4th jobs books. I find it very scummy to implement a system for the highest lvls in the game to be based off of so much rng. Nodestones are very rare to find, and skills you need randomize at very low rates. At least with the books you can apply them to the skill you want. With nodestones, the player have no control.