Greenskin is one of those in-and-out type legendaries. I think he started seeing some play when Pirate Warrior started becoming a thing for the very first time, then got relegated to optional. Showed up again when Kingsbane was at its peak, went quiet again when that got nerfed. Now that Pirate Warrior is back in Standard (and Bomb Warrior), he’s back too.
Giving weapons extra dura is a fairly unique effect usually limited only to Warrior, so having it neutral has some applications. I’d say he’s a simple but interesting addition to certain decks, but probably pretty optional. In comparison, Bomb Warrior is missing one of its biggest cards if Blastmaster is not in it, whereas Greenskin is a “safe” craft on account of being a neutral classic yet also a little less missed if he’s not included in the deck.