That nocubes mod is basically applying the "marching cubes" technique... which can result in some very odd results. I'm not entirely against it, but one of the issues with something like that is you never know what result you're going to get at runtime, and you have to distinguish which blocks will be affected by it. You dont want a player's sexily crafted altar to become a blocky marble hillock.
Voxels are so ubiquitous now that I dont think 'voxel game' means 'minecraft' anymore... it's the whole thing... 3d voxel building game = minecraft even though it really shouldn't... space engineers is a 3d voxel building building game but no one would say it's 'minecraft in space'