Have they ever figured out how the Romans made concrete and got away with not using rebar ???.
Tangentially - it's not that we can't make concrete that way, it's that for many structures we're building of concrete, building to last 100+ years is over kill, and would increase costs drastically for a building or structure that will most likely be torn down before it reaches its life expectancy.
TLDR, the asymmetrical 4-2 storeys shape is the result of that earthquake when the top of the part of the building built on softer ground felt down.
tl;dr: we took a long time to realize that the Romans didn't use potable water, they used saltwater; the volcanic ash they had access to was also very important