I would love if they added a book, in which you could learn the code of the enchant table, it wouldn't be easy to craft nor learn but it would be awesome.
I also think they should add more activity to the villagers.. like they cut down trees, actually eat, replant stuff, make tools, stuff like that.
Lastly they should add steel.. it has the same durability as obsidian but is faster to break. And with that would come iron bars, or something you would have to craft to actually craft the steel block.