Yeah, there are a handful of "centrists" in both parties, but for the most part, the Republican Party is dominated by it's hard-line "conservative" faction and the Democrats are dominated by...well, the Democrats aren't dominated by anyone except people who are opposed to the Republicans.
What happened to the days of "bipartisan cooperation" on issues, particularly on issues that didn't result in really bad outcomes? What happened to the influence of Congressional Committees?
Congress went from passing/debating ~$20 billion stimulus packages in 1993 and fretting about Napster/Elian Gonzalez to ~$870 billion stimulus packages in 2009 and trying to dominate entire sectors of the economy.
The latter is more difficult to find common ground on.