Yes, I don't think the limitation is stupid. You bizarre strawmen about druids wielding iron stave and having four metal prosthetic limbs are utterly unconvincing as they simply are not things that would happen in the first place, at least not commonly enough that it would matter.
Furthermore, I don't think druids are underpowered, they don't need a AC buff. They're one of the most powerful classes in the game.
But hey, if it is not about powergaming, then certainly you would be fine with you druid getting to wear a metal armour that has rules of hide armour? Good compromise?