The problem with our current political system, what makes it so dysfunctional, is not partisanship or a lack of collegiality between the parties. The problems are the filibuster in the Senate and unequal representation in the House and Senate, which prevent a party that wins a majority of the vote from implementing its agenda, so that the voters are able to ratify it or reject it in the next election.
I agree with this. What has happened is that the political system has evolved over time. The problem is that our system of government has essentially remained static over that same time period (save for some minor Congressional rule changes here or there). As you say, the broad coalitions that used to make up the two parties have given way to the ideological spectrum with much higher party discipline. The political system is now essentially parliamentary in nature. I think the dysfunction in Washington is a result of the lack of constitutional evolution in terms of Congress and the Presidency. The last truly significant reform to the system was the direct election of Senators, now over 100 years ago. Elimination of the filibuster and partisan gerrymandering would be great reforms, but it wouldn't be a cure-all for the dysfunction.
