Well, since this thread is alive again, I'd like to blow up about something:
Mining at the moment is a little uneventful and a bit of a grind. We plan to remedy this by vastly increasing the number of underground encounters, dungeons and microdungeons you’ll encounter whilst mining. Many of these dungeons will contain some of the loot you’re looking for whilst mining and save you from simply tinking away at blocks for hours on end. We’re also going to increase the range of monsters underground to mix up the experience and look into benefits for sustaining existing mines.
You know, they could probably fix cave generation to make them more diverse. Maybe some stalactities or stalagmites along the ground for some hazards, lava lakes of varying sizes, some other interesting hazards like- oh, I don't know, biome-specific stuff. What if lava planets had some unremovable holes on the cave walls scattered about, releasing steady flows of lava over certain periods? How about jungle planets that have flora everywhere, with brambles and plant monsters with vines to grab on to? Maybe huge collapses of sand on desert worlds, or slippery ice combined with deep chasms, or massive flooded areas, or poison gas, or massive pools of radioactive crap that screw with your stats, or giant effing tentacles that burst out of the walls and throw you around?
While they're at it, some aesthetic stuff would be nice too. Like pebbles and mushrooms! Every underground area needs those. And what about crystals? They're shiny, and valuable, and could probably be used in a whole lot of sciencey or magical stuff. And let's not forget the aesthetic value of skeletons and flowing water.
But eh. Who cares about the journey, kids these days just like to have some stuff handed to them, used to kill a few baddies, then used against some big baddie who leaves them with a giant "YOU'RE WINNER!" And that's what we'll just do here, give players a few big underground structures filled with all the stuff they need to get out. Oh, and hazards? Let's just place some electricity here on the floor in this abandoned lab- no need to worry about the abandoned look, by the way, you can just make it look all pristine.
There. Perfectly good underground.