Personally I think that they should be back in game, but they should be on mumakil. Simple, current situation with mumakil and free slot on him is little absurd. Were orc archers ever in history of Middle Earth be able to ride mumakil and shoot from his back?
Idea is good, always try to make balance between Lore/desire/idea.
P.S. And currently in game when you put Black Uruks at mumakil, simply it's op and absurd.