Auto looting a mob will increase leveling speed for the expansion. to enable it = Esc, Interface, Controls, Enable Auto Loot. I'm including this because sometimes the simple things are missed. I, sadly, went 3/4 of the way through WoD not knowing that hitting the space bar for my mission tables is much MUCH faster than waiting it out. (i never claimed to be smart OKAY) =P
Something to keep in mind as well is that this will make enchanting materials more valuable, since it is likely most players will now simply scrap their boe greens instead of getting them disenchanted. Also redundant dungeon/raid gear can be scrapped rather than traded to the (guild) enchanter in the run. Less stuff gets disenchanted, meaning there will be less ecnhanting materials, meaning their value will rise. All the more reason to DE rather than scrap as an ecnhanter.