In all reality what's the difference if you select the item from your inventory or a toolbox/fridge? Your still just opening up a menu and selecting the item.
Well, with the crafting system you could just pick the item/weapon you want to make and it will check first your inventory then the toolbox for the item, instead of you having to rummage through your containers for the part you saved, taking it out, then using it with the workbench.
Its not a huge timesaver, but it would be convienent.