We've lost more than intricate ornamentation. We've lost ornament as a thing that regular people 'ought' to be around. I think it's interesting how Americans often assume that ornament is meant to display wealth, and is thus some sign of show-offness. I think the opposite is often the case. Ornament displayed in public is actually meant for public enjoyment. It's a form of philanthropy when done by a private wealthy individual, and a form of public works when done by the state. Humans deserve to live in beautiful environs. We should strive for that, but we've regressed greatly, with even wealthy neighborhoods being devoid of nice beautiful public spaces (except for a handful in particular cities).
The average Roman peasant would have been exposed to more ornamentation in their life than the typical American. Whereas Americans would be driving by endless McDonalds, Starbucks, and strip mall number 523, a Roman peasant would have seen the great triumphal arcs, the facades of the great buildings, etc. It's just a complete loss. Anyone who's been to an older city in Europe or Asia knows exactly what we're missing. When ornament is a thing that exists, whether private or public, the whole public enjoys it regardless.