The original intent of the US political representative system was pretty much in line with what you suggest. Over time, the costs of running such a system with

The original intent of the US political representative system was pretty much in line with what you suggest. Over time, the costs of running such a system with a hugely increasing population and senators/etc who enjoy wielding more and more power stopped any serious moves to keep the ratio constant. Also, those who buy influence in congress would of course prefer there to be fewer people to bribe(lobby, whatever) for their laws, so they'll always be anti any suggestion like this.