That's what the new terrain gen code does, it adds loads more variance to y-values, possibly too much now, but the steep slopes that creates isn't too compatible with the cave systems. Where you get sheer cliffs is where the difference between those two points on the y axis is close enough to be considered zero from a voxels' point of view

Alos, the new code makes the landscape much more 'mottled' with biomes, which probably doesn't help.
In my opinion, he needs to double the scale of the Biomes generated, and probably reduce the Y-Variance in the terrain gen to around 75%.
Still, it makes for some interesting scenery and building opportunities, which is probably the intention
