PING!
Interesting premise. Gotta read it during my lunch break.
What makes the courts, especially the Supreme Court, "aristocratic" -- even autocratic? First, lawyers and judges are expected to have special knowledge and skills that isn't required of senators, congressmen, or Presidents. Secondly, judges and justices are appointed for life and never have to worry about reelection. Third, Supreme Court justices can overturn federal and even state laws -- a power that the Senate certainly never had, and Senators could only dream about.
So the "aristocratic" potential was present in the courts from the beginning. Even if we still had an indirectly elected Senate, there'd still be activists of one sort or another trying to get their own way in the courts when the majority didn't agree with them.
I've long thought of the US government as a "mixed regime," fusing the various forms of government in hopes of getting the best from each.
I'll also note that when the Senators were elected by their state legislatures, they were representatives not of their citizens, but of the citizens' government. Now state governments need their own lobbyists in Washington to do the job the Senators were supposed to do.