Well, you have to differ between Orbiter and KSP in one very important aspect: Orbiter uses a real solar system (our own) with real topography.
KSP uses a fictional (but inspired on our own) solar system, that has fictive topography.
That makes it easier to use procedural terrain, since it is its own reference.
Would you recognize Olympus Mons, if it is made by procedural terrain?