I'm not spoiled enough to remember the non-obvious ones, and I don't remember needing to. Definitely not required for smithing, smithable items have material in the name, if not they are iron or not metal. With mist elves I test for iron by wearing (after making sure it's not cursed of course). I mean, I agree it has some purpose, but just not enough to justify having it as a skill, and none of the suggestions really strike me as the solution, so I'm for removing, with maybe metal recognition being given to Smithing skill as a passive or something.
Also, concerning new players - they might waste level-ups on it before realizing it's mostly useless.