Ironically, one of the major themes of modern(ist) architecture is eliminating ornamentation and focusing solely on the hierarchy of spaces buildings create and what their uses are. "Form follows function" comes from modern architecture.

(Not all of it is successful! And like, it's hard to say Calatrava is about that. But we hear more about the failures than the successes in modern architecture, and conversely less about the failures of classical architecture, b/c survivorship bias.)