This is an excellent idea. If simple motorized wheels were implemented in build mode, this could be easily achieved! As it is, I guess simple hover-craft could be made, but they would be clumsy with the current way building is. I mean, it\'s meant for star exploration! I agree though. This idea kinda rocks.
There are certain advantages, I imagine. For instance, moving from point A to point B on a planet could be very clumsy with a space craft, and could be too slow on foot!