Inventory issues stem from redundant granularity in crafting/trading systems. You don't need 50 types of wood, stone, fruits, birds, fish, and so on in the earlygame which I remind you is being completely blazed through via quests and challenges. You get the same issue with some raids too, Alexander drops a huge amount of different resources for equipment that is already redundant by the time you end up doing the quest.

That said, crafting materials should be utterly segregated from the main inventory. I'm done playing inventory tetris, limited inventory is for survival games, not MMORPGs.