The second problem with this question is Bowers not imagining what a GOP President and GOP Congress would have achieved with the elimination of the filibuster. You thought the actual Bush tax cuts were bad? They would be TWICE as bad without the filibuster. And twice as hard to undo as they would have been passed in regular order, meaning that to undo them would require passage of new legislation
You can be for eliminating the filibuster on principles of democracy, as Ezra Klein is. But you can not be against the filibuster, as Chris Bowers is, based on advantage to Democrats and progressives.
There are all kinds of problems with this argument, some of which Kevin has addressed: most notably, it is well understood in the political science literature that most welfare state programs create constituencies that make them very difficult to repeal even in Parliamentary systems. A few other points. There’s an additional asymmetry from the fact that liberals are simply more likely to want to adopt new federal programs that provide assistance to non-powerful constituencies. Defense spending isn’t vulnerable to the filibuster; attempts to provide better health care to lower-income people are.
At any rate, the fact that the filibuster made public policy marginally less bad when the Republicans had control of the government (and only very marginally: note that the filibuster wasn’t necessary to prevent the privatization of Social Security, and also note how little of the major parts of the Republican agenda was successfully filibustered) isn’t a serious argument. No way of structuring institutions can entirely prevent bad politicians from doing bad things when they get into power. It’s a question of net benefits, and the history of the filibuster makes it overwhelmingly clear that it’s not just bad from the standpoint of democratic principle but is also bad for progressive politics. It’s always been much more useful for reactionary elements and on balance always will be.
Bowers was right; the Democrats screwed up by not doing what they could to put the filibuster on the road to destruction (and that goes triple since the Democrats didn’t actually get anything useful from the Gang of 14.)