Hmmm...I can't say I have seen any real improvement in modern methods at all? Different yes, but "better" seldom to never...in the big picture...

As for "fossorial architecture"...Humans have been building "under ground" or into cliffs for about "forever." Some of the systems of architecture are very complex.

Having about 5 "direct builds" of these types of structures and countless consults and observations done over the decades of what folks would call "earth-ships," I can say few last very long (outside arid regions) that don't end up with very serious interstitial moisture issues and related challenges...

Great concept...seldom works...but can be made to work well if "traditional modalities" are implemented...and/or appropriate biome type is chosen for the location...