Ok, so no answer there. It being the oldest actually cuts against your argument, other nations looked at our system and decided not to use that system.
Our founding fathers were students of Ancient Greece and learned from their early experiments with democracy.
Not an answer.
Our system does what it was designed to do, force compromise. Extremism is minimized.
Popular vote for President doesn't change that. Again, we have just one election that has to operate this way. The Senate and Congress and all that still operates the same. This is just about President, one office, one person. One vote per citizen.
This is why I feel like the arguments against popular vote are all vibes and Republicans who want to maintain minority rule. Same as why they wont' support eliminating gerrymanders, they only care about power, not principles.
It's easy to eschew popular vote when you don't actually care about democracy after all!