The past year has been a spectacular demonstration of the crippling effect of the filibuster on America’s ability to deal with, well, anything.Krugman is wrong. We've had the filibuster in the Senate since 1789, and this is not the first era to feature bitter partisanship.
While a legislative minority can in theory use a filibuster to block majority party will, it comes at a high cost: the minority party effectively shuts down the Senate for the duration of the filibuster. A filibuster is as well an extremely visible and dramatic action. A filibuster can thus work politically only if the people as a whole support the position of the minority party on a particular issue. If they do not support the minority, a filibuster hands the majority party a potent partisan weapon.
Our superficial political problems seem more obviously due to the weakness of the liberal faction of the capitalist ruling class. Had they even a little bit of partisan will, they would welcome a Republican filibuster, especially over an issue as popular as health care. (A deeper problem is that the voters consistently reject politicians who pursue an explicitly populist agenda, precisely because the narrative in the commercial media brands such politicians as unserious and, ironically, as mindlessly partisan. This narrative is even seeping tacitly into the liberal intelligentsia.)