Would be cool if you loaded up an infinite slate map, with the flat ground already done.
When entering edit mode, the grid would appear, but, you get a handful of terraforming-tools.
These could be ones like smooth, lower ground, raise ground, create water, create cube and so on.
There could also be diffrent smoothing opinions and ways to make a specific area smooth.
I support the idea to 100%, and if it isn't officially included, will there be a way to implent it as an add-on?