Bingo! (to use an Americanism). The authors of the Constitution looked to the Roman Republic for an example. There, a long slow process that was relatively easy to derail kept the situation stable (spoiler: the Republic didn't last).

They had no idea political parties might arise (they expected - and guarded against - regional factionalism. And this was prior to our Civil War, so the Constitution was about federalizing multiple sovereign states (similar to the EU). The Electoral system came out of that (smaller states having as much voice as larger ones).

Aaaand you're right - it's pretty outdated. It does include a mechanism for change (amendments) making it a 'living' document - but the current situation is so deadlocked that any additional of those are highly unlikely.