As the article hinted at the simple answer is Car Dependency. Suburbs are regulated and built to accommodate cars now and not people. The topic is explored thouroughly on the 'Not Just Bikes' youtube channel. https://www.youtube.com/c/NotJustBikes which uses information from urban planning group 'Strong Towns' https://www.strongtowns.org/ .
Nope, the article specifically addresses your point: > consider college campuses and their central quads, which typically do not have automobiles even today. The ones people admire are the older ones, not the newer campuses, which tend to be functional but aesthetically mediocre
Admiring the old brick styles of the ivy leagues is simple confirmation bias due to their academic prestige. There are plenty of beautiful Modernist buildings, it comes down to if the college is willingly to pay for it.