Mostly this is looking at architecture as urban sculpture. That is relevant, but the most critical experience of a building is on the inside. Modern designs spearheaded modern interior spaces including spacious corridors, atriums for exposing important views and improving navigation, and other such features. More than that modernist buildings are good at presenting functional spaces with a minimum of details to interfere with usage and customization. Different uses can add decoration or functional features as necessary as there is plenty of space available and no ornamentation to interfere with.
And then there is the issue of construction. Many older designs use materials and methods that are either out of date or expensive to replicate with currently popular building materials. Simply going back to older designs is not a practical option for most buildings. There has to be some balance of old ideas with newer methods.