Craft material storage akin to GW2. If you try to level Mining, Botany, and Fishing at once, you eventually won't have room on yourself and two retainers. And given the sheer volume you wind up producing to level these things, you will almost always have excess even if you did refine them into crafted goods. There are some exceptions like more frequently used materials for cloths, leather, etc., but I don't think I'll ever need 99 iron sand, but I'd hate to sell it just to suddenly need some later and have to buy someone else's 99 stack.
To take that one step further, I also love how the crafting mats are automatically pulled from storage and so there is no need to run around with a ton of random crafting mats in your inventory. They do limit you to crafting at specific stations scattered throughout the world, but I prefer their system hands-down to that of FFXIV (in regards to the material management).
In my limited XIV crafting experience, I seem to always forget one crucial mat or I have grabbed the wrong amount. At that point I either have to run back to my retainer or I just buy the item from an NPC/market board - depends on how lazy I'm feeling at that particular moment. I would love to be able to take that part of crafting out of the equation. Edited, Sep 24th 2013 3:48pm by mabiche