I think more underground things should be added.
And not buggy things like Abandoned Mineshafts, Ravines and Strongholds, good, challenging-to-find things like Lapis.
I mean, it is Minecraft.
Though literal mine shafts would be cool if done properly, just stone brick structures stretching from bedrock up with a hollow center and the occasional chest filled with ores/refined products that get better the deeper you go (i.e. at the top there's iron and gold but the deeper you go you get diamond, lapis, redstone, etc), but the deeper you go the harder it is to go because parts could be melted by lava or broken down from abandonment.
Poll