Guild Wars handles the crafting mats in a very nice way. They have a crafting mats tab that lists all crafting mats and you simply buy increments of 250 increases. What starts out holding 250 of any crafting mat then jumps to 500, 750, etc, etc with each additional unlock. Alternatively, increasing stacks to 250 from 99 would free up a good amount of room, but I agree, more tabs are needed if we stick with the 99 size stack. All my legacy tabs are filled with crafting mats and companion gifts.