Steel is way too easy to make for what it is, you just need some rocks, iron and charcoal and you get a metal that's worth it's weight in gold and in a tactical class all of it's own, it just seems a bit cheap. How about when a dwarf does the task there's several possible results like quality levels in other tasks and based on the furnace operator skill level of the dwarf? Something like Normal=pig iron again but some material is lost, Well-crafted=wrought iron which is not weapons grade but does have a higher value than iron, Finely-crafted=brittle steel which is worse for armor but a bit better for edged weapons than iron, Superior quality=Steel but it's a bit worse than current steel and finally Exceptional/Masterful=Dwarven steel which is the same as the steel we all know and abuse.
Allowing furnace operator skill to effect things opens new possiblilities as well perhaps less skilled operators might tend to get less out of the ore and not separate the more valuable materials, for example a newb melting down some galania might just get lead, or not get anything out of gold ore.
On a different yet related note the metal density in ore vairys greatly depending on the type of ore, it seems strange to get as much gold out of a rock as you get iron out of hematite, to make the rarer metals more balanced(seriously, if you set up on a gold mine you can just buy out every caravan from the second year onwards) and make mining logistics more difficult you could get different grades of ore independent of vein size(perhaps a gradient from the outside of the vein in?)and have different ores tend towards different qualities. I think it'd also add a bit of depth and complexity which Dwarf Fortress obviously needs more of.
Also mabey make building up skills slower? Esspicaly with the later levels like the master levels. It just feels a bit weird for them to go through to legendary in a year. Perhaps also have a bit of a penalty for dwarves new to the skill like wasting materials or making xLow qualityx items.