The post is interesting throughout, but these are the two best paragraphs:
You only need to impress someone when there is asymmetric information, where that someone does not know how great you are. Shah Jahan needed to build big because the targets of his attention did not know the GDP of his dominion and his tax/GDP ratio. In this age of Forbes league tables, Mukesh Ambani does not need to build a fabulous structure for you to know he’s the richest guy in India. A merely functional house suffices; a great feat of architecture is not undertaken.
Accountability The incremental expense of going from a merely functional structure to a great feat of architecture is generally hard to justify. Hence, one might expect to see more interesting architecture from autocratic places+periods, where decision makers wield discretionary power with weak checks and balances. As an example, I think that Britain had the greatest empire, but the architecture of the European continent is superior: this may have to do with the early flowering of democracy in the UK.