It is illogical and unscientific to assume that Modern architecture (which I am capitalizing to distinguish from modernity as an era, for Art Deco is certainly modern) does a better job of maximizing the beauty of "form following function." For example, the Seagram Building that I trashed in my essay was famously unpleasant for the people working in it! Mies was a stickler for having uniform blinds in the windows that could only be set to a few positions, so to counteract the intense sunlight, the people who worked there would stack up furniture against the glass walls to shield themselves. So much for functional.

But beyond my fondness for mocking that particular building, this is the more important point: humans evolved to delight in ornamentation. This is most likely a result of sexual selection, which causes rapid evolution towards ornamentation in both our species and others (most famously birds like the peacock). Matt Ridley explains this phenomenon expertly in his book "The Red Queen," which I recently published a much shorter essay about:

So the assumption that ornamentation has no function is absurd. In humans, the ornament we evolved was our big brains, with all of the creativity that goes with it. This is not to say that every artist is simply sexually signaling — our behavior is complex, so our analysis should not be so reductive. What this means is that our desire for ornamentation is fundamental to what we are, and to dismiss it as lacking function is scientifically ignorant.

We can also consider ornamental architecture as one of Chesterton's fences. Perhaps we struggle to fully explain its function, even if we have useful clues like theories of sexual selection to help guide us. But humanity has made ornamental architecture in every culture in the world for millennia, and it takes a great deal of arrogance to disregard it now. As Chesterton counseled, “To which the more intelligent type of reformer will do well to answer: 'If you don't see the use of it, I certainly won't let you clear it away. Go away and think.'"

I believe in individual genius, and the International Style ain't it. The Chrysler Building was quite literally a monument to Chrysler himself; the Seagram Building was the brainchild of a socialist who strove to create "perfect worker housing." That so many capitalists got caught up in that fad is a terrible irony. If outside the fictional world of The Fountainhead there were some real traditionalists trying to stifle individual geniuses, then that is because they misunderstand how the traditions they love came into being. Here's just one example: Filippo Brunelleschi was a genius who figured out how to create the largest Cathedral dome in the world (at the time), and Renaissance architecture is indebted to him.