The Atlantic's Joshua Green, George Packer adds C-SPAN to the list of reasons why the Senate has ceased to function, putting alongside air travel, an influx of former House members, reducing filibuster requirements, perpetual fundraising, and so forth.
All of these explanations ignore the obvious root cause: Senators ruined the Senate. Orrin Hatch, Ben Nelson, Olympia Snowe, Lindsay Graham, and all the rest of the bunch are human beings. Indeed, they're Senators—the type of person who is said to pride both comity and independence from party! It cannot simultaneously be the case that the forces of partisanship are unstoppable and that Senators so cherish the coziness of their august institution that nothing else ranks higher on their list of values. When mandarins like Howard Metzenbaum (D-OH) were in their heyday, the Senate operated on cultural norms that the filibuster was a rarely, if ever, used practice. Even though nothing in the rules prevented it from overuse, the men and women of the Senate decided not to go there. Today, a different set of Senators have made a different choice. It's tempting to blame this change on some cultural or structural trend, but doing so ignores the agency of the flesh-and-blood people who populate the Senate.