I recall earthen covered/buried/walkout houses gaining popularity in the 70s. My father was an architect and would point them out to us often. He'd rattle off all the benefits of living in one, and any south facing hillside with a nice view was a prime candidate. The main concerns were the sides that don't have daylight, and fire escape egress. Other than that, it could be done very nicely, was always quiet, easy to heat and cool, etc. You didn't have to bury it completely, either. You could have two sides exposed. Or an earthen berm up a few feet. Anything to save exposed walls to the elements. Stuff like that.
He also mentioned "Your mother is claustrophobic and would never live in one." Which was true.
