"doesn't mean that we should give the rest of the state disproportionate power."

Is it in the best interests of all the people to have proportionate power? I believe so.

The EC is an abstraction, which philosophically and practically takes choice away from individuals. Population centers having more power than rural areas (even when they are the geographical majority, otherwise) is a proxy for land-owners having more power. While, ironically, land-owners (like farmers) often tend to be poorer than city-dwellers in absolute terms, I don't believe they should have some sort of relative power difference.