The issue is we are a nation of states. The House represents the people and they have certain roles. The Senate represents the states and they have cerrtain roles. If we make congress strictly democratic representation then there's no need to have two houses in our legislature.... and at that point why we even have states? The idea is that states are more than geographical boundaries. Why do we have one Montana or Wyoming or Idaho but two Dakotas? I'm sure there were political reasons behind that, allowing the overall region of Dakota to have 4 senators instead of 2, maybe having to do with slavery? I don't know the history but it wouldn't shock me.
This would require changing the constitution which requires the states to agree to it.... won't happen. They're not going to give up power. IT's also why the only real way to change the electoral college is through the popular vote pact that states are individually signing on to, which will also be challenged in court as soon as it's implemented, if it ever reaches that point.