In my personal opinion, I think Minecraft could benefit from more class options (not mandatory classes). We already have a warrior and almost have a ranger. Here are just some ideas I had.
Ranger: We already have a bow (and crossbow soon) but I think the tipped arrows could use a bit of work. I think there should be a button you can press if you have a Quiver in your inventory to cycle through what kind of arrow you would like to use (i.e: Press G while holding a bow/crossbow to cycle through shooting regular arrows, healing arrows, poison arrows, etc.)
Mage/Wizard: I think it would be cool to see some tomes/hand cast spells the player can learn/find through out generated structures. I think they could be learned by discovering a special page or something or by combining certain enchanted books together to get a tome. Maybe you have to combine enchanted books with paper to get a page, and once you get 2-3 you combine it with a piece of leather in the crafting window to get a tome based off what pages you put together.
Those are the only 2 things I have currently. I'd love to hear some feedback on my ideas or other ideas you guys have!
I think you have mistaken the game for something what it isn't and not trying to be.
I get where you going with this, but…this is not that type of game.
Besides…what about me? Most of the time, I'm out there building something, mining, transporting stuff, all while smelting. No combat. If so, then it's on construction site, where I didn't bother to put lights, but that's rare.
Classes in RPGs are about restricting player from getting too overpowered by being able to use all abilities at once (like in Ultima Online where everyone ended up being a tank mage in heavy plate and tier 8 spells). MC is just not that sort of game.