Right now, people have control over US senators: They vote for them.
How are 35 state senators (in the case of the state of Colorado) any more representative of "the people" than people going to the polls and voting for someone?
If you think that members of the US Senate should have remained selected by state senates, rather than popularly like the US House, I respect your opinion, but I think state senates are just as likely to appoint party hacks or ideologues as the voters of the states are. And, US senators appointed by state senators are beholden to an even smaller number of people than if they were directly elected.