Ancient Greek-style democracy -- where every citizen votes on every important issue -- can now be implemented in the US and any European country, with ease. It's not like we don't have the technology. Why do we need corrupt intermediaries? To simplify things a bit, it is because we're going to get oligarchy or ochlocracy, and the oligarchs want to make sure they're on the winning team, whereas direct democracy is a path to ochlocracy within a mere handful of years.
The Ancients knew all of this, of course.
All that said, a state's form of government has very little (in some cases nothing) to do with that state's ability to benefit from material progress.
It's a real laugh to suggest that our ancestors were "suffering enormously" on account of the fact that they were ruled by a feudal lord who descended from his mountain fortress once a year to collect taxes in the form of a handful or two of grain. Our ancestors had a place, a duty, a strong faith, and a connection to their superiors and inferiors. Large families, festivals and feast days, homes full of music. On balance, they were probably happier than modern man.