People have been creating their own, using the Fatten Tool, since the game released. Check the Settlement Showcase- Settlement Showcase - Share your creations!
Quite a few examples of cliffs created by players there.
And the barn has a pulley system shown on front of it, which would imply that we have the technology to at least create a simple pulley system.
The issue I see is that it will require Crate to add a new building type with at least one upgrade probably, that will only be used by players who enjoy doing serious terraforming to create their own cliffs. Something not all players get into. Though it might be an idea for a future update or small-ish DLC for people to buy if they enjoy the idea.