This has been suggested numerous times, including ways to effectively implement it in the current skilling system. If it's not been updated by now, I honestly don't expect it will be until a major skilling update rolls around.
Your best option for training smithing, presuming nothing has changed since I got 99, is to: (1) smelt Iron bars in the Resource Area or the Donator Dungeon, or (2) smelt bars and make platebodies. I, personally, smelted bars on the Skilling Island (the Donator Island bank chest/furnace spot is marginally better now) and smithed them into platebodies at the anvil nearby the Dareeyak teleport in the Wilderness.