Since both houses of Congress are popularly derived, why put up with the bother and dissension? One house can do the will of the people.
Deliberation and agreement would be easier. Wouldn’t a single house Congress “get things done?”
The House represents population interests and the Senate represents geographic interests. This is why Congresswoman Shelia Jackson Lee of Texas will never be Senator Shelia Jackson Lee of Texas, and Congressman Scott Garrett of New Jersey will never be Senator Scott Garrett of New Jersey. They represent vastly different constituencies in the House and Senate.
However, your argument would make sense when it comes to merging the two houses of many of those state legislatures you want to give power to.