I think Treasure Goblins or something similar should be added, where a very rare mob spawns completely randomly in the world and drops a ton of items and coins for the players that are there. I think this experience would be like no other and treasure goblins add a special factor to the game as you can come across one at any time, or go treasure goblin hunting
. Nobody ever has a bad time coming across Treasure Goblins or something similar in other games.