The original plan of the Constitutional committee was for the House members to represent the people directly and for the Senators to represent the sundry state governments, not their people directly. This had an exquisitely subtle effect of moving national issues down to either the state level or directly to the people. The idea behind "democratizing" this in the 17th Amendment was that the Senate would be more directly accountable to the voters, but with a six-year term of office that simply hasn't been true in practice. But the marginalization of power for the state governments has been very real.
The flip side of the notion is that corruption would be more concentrated at the state level as well - a single power group sufficient to seize control of a state would have a direct and unopposed line to the federal government. Montesquieu among others felt that local corruption was more easily dealt with than concentrated, distant corruption - I think he may have been correct in this - but that doesn't make it any less corrupt. Without direct election it is easier for such a state-level power group to influence the federal. With it, the state government loses influence and the corruption moves to a less accessible level. It's a choice for realists, IMHO, and the idealists made it and have ever since been burned by it.
Just my $0.02.
That may well be true. But they would've had a different mission. Rather than pandering and simply seeking re-election, they would've been there to safeguard the interests of their states -- and the outcome of legislation would've been quite different.