Agreed - I would like to see more editor extensions than “Content”. Anyone can make content in one shape or form.
There are a fair few plugins that are better especially in the road department that I Would like to see for Unreal.
Take a look at this -
As for Voxel Terrain -
Plenty of videos if you Google VoxelFarm.
There is also PolyVox - See here.
Which is opensource under the Zlib license.
Anyway - Just my 2 cents.