The shader system should be converted to the same system that armor and weapon mods currently run on. When you get a shader for first time, it's permanently unlocked and in your inventory, When you want to apply it, you just pay a small amount of glimmer.
I don't think anyone enjoys the laborious task of deleting huge stacks of shaders. This has been a problem since early D2, and I think the new mod system is a good template to fix it.
-
They should be more like they where in D1. Make them Unlocks instead of Consumables, and make them more like the Emblems so that we could dismantle or reacquire them from the Collections. Move the cost of acquiring them to the application of them to keep the game balanced. You would no longer have a stack just the one reusable one. This would prevent us from getting more and more of Shaders we don't want as once unlocked vendors wouldn't just keep giving them to us.