Obstructionism is usually the point of bicameral legislatures. Checks and balances, and all that.
One justification for district representatives is that the parties will have to take into account the specific interests of a given district in order to win. In addition, the number of people in a district can vary; so that sparsely populated regions are not always ignored in favour of more densely populated ones. States like Alaska would be completely irrelevant if it didn't have two senators like everyone else and the bare minimum of 3 votes in the electoral college.
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