Tower defense, crafting, looting and questing are the bread and butter to this game. Digging is not a core pillar and mining could easily be done without it as well. You could still use foundation blocks to level out a nice place to live or even flatten vertices of static terrain some and have 95% of the game, without 95% of the trouble.
Anyhow we might add it as an option at some point, and use telemetry to see how many people run that version and base our decisions on facts not emotional responses.
IMO a year after its release, 80% would be playing static terrain version because of better visuals, better FPS and they don't give a crap about mining. We could still plop down "earth blocks" to fill in spots etc and make trenches your just building it up instead of digging down its the same net base, just elevated higher. There could be craters from nukes you fill in and have a "basement" or "bunker".