1. New mob heads for: Zombie Pigmen, Husks, Strays and Drowned. Doesn't make much sense that these zombie and skeleton variants lack collectible heads.
2. Make witches a part of the Illager/Pillager faction; Capable of spawning in woodland mansions and in patrols.
3. Add a small chance for Skeletons and Strays to wield a crossbow instead of their classic bow, making night time battles a bit more interesting.
4. Add very rare mob variants such as Unicorns, Toucans and Sphinx Cats. Pursuit of these special pets would contribute greatly to the adventuring aspect of the game.
5. Complete the spawn egg selections with the few missing mobs: Ender Dragon, Iron Golem, Snow Golem, Wither Boss.
6. Add the RGB dyeing system to all dye-able items; Wool blocks, Concrete, Carpets, Banners, Stained Glass, Stained Clay etc.
7. Add dye-able flower pots.
8. Camels for the deserts, A neat in-between for the Llamas and Horses; Basically just a Llama that can be ridden and controlled but doesn't benefit from armor.
9. In a similar vein of thought to #3, Add a rare chance for Pillagers to use an enchanted bow instead of a crossbow.
10. Add Goats to the mountains and deserts, Can be bred with virtually anything and drop Goat Meat for small quantities of food.
12. Add Ducks and Frogs to the swamp, Ducks being new farm-able animal mobs and Frogs being mainly ambient mobs, Perhaps dropping Frog Legs as a small food source and alternate means of making Jump Boost potions?
13. Allow Pumpkin Pies to be placed and consumed like Cakes.
14. Allow you to eat a whole cake in your inventory if hunger is sufficient.
15. Bring leather horse armor over from Pocket Edition, As well as its super cool dyeing system.