The ‘Wedding Cake’ style of architecture requires a lot of ‘fondant icing’ stuck to the outside which is made from expensive and highly labour intensive materials, hand carved stone typically. To take my cake metaphor to far, you can put too much icing on it and it becomes a sugar sculpture full of cardboard props and bits of wire, not something you would enjoy eating.

A well designed building in the renaissance style is beautiful but this style also places arbitrary constraints on the design, like symmetry, which make them inefficient and very hard to design convincingly while still meeting the brief for the modern spaces inside. That’s why they’re not built like this anymore. There are a plenty of badly proportioned late 20th Century faux classical buildings out there and to me they stick out like poor typography does to a graphic designer or bad punctuation for an editor.

As other comments have pointed out the big problem with buildings in many US cities and European suburbs that developed after ww2 is mostly with urban planning failing to create walkable cities. Spain and Holland have had different approaches but I think they are the most successful in Europe.