In the 1.9 pre-release, you introduced the first utility mob, the snow golem. The concept of it is very simple: a mob created by the player which serves the player. I think that idea has a lot of potential, but the snow golem is relatively useless. Perhaps you could introduce more golems or an entirely different mob. Any more utility mobs would be a great add to the game and will be appreciated.
Maybe you could mine some sort of life jewel which would be VERY rare. with it selected, you could right click some types of blocks to create utility mobs. for example, the dragon egg would become a baby enderdragon. You may think this idea is stupid, but I think this would add a lot of fun to my worlds
Support! There should be Fire golems who throw blaze fireballs (crafted with 2 obsidian) and clay golems who fight and act like zombies. Also, snow golems need to stop leaving those annoying trails, and they shouldn't melt anywhere except when in lava.
It makes me sad.