Do you think bulldozers and or other harvesting vehicles be a good addition to this game?

For an existing non-cheating option, try TNT. I used it in some areas when making a grand subway-like tunnel. Throw it into a hole a couple blocks deep, and you’re destroying blocks faster than with hand tools at least.

A bulldozer could be cool but it seems unlikely the ones in the game would be drivable in vanilla due to their size.