Interesting analysis. So the problem isn't with democracy per se, but with overly centralized democracy. As someone who's lived all his life under a parliamentary democracy [like those too-vaunted "Nordic model" countries are], I can say that relatively centralized democracy requires the ordinary Joe to defer to authority.

Yep: the "Nordic model" structure, along with the more British version of parliamentary democracy, requires a deference to authority that would drive the average red-blooded American nuts.

In addition, centralized democracy only works fairly well (i.e., without tumult) in a culture that's a lot more conformist than the American variety.

Federalism - decentralization - was the key to making democracy work in modern times, as you so well noted. The Founders were well aware of the political philosophers who concluded that "pure" democracy only works at the city-state level; it works best in places like small towns where "everyone knows everyone". It does not scale well; when a democracy gets to the size where voters have to be divvied up into abstract categories, democracy does get creaky.

FWIW, the modern justification of democracy was that it provides a system to ensure the peaceful transfer of power from one government to another: in other words, it nips civil war in the bud. That's all.