Someone said this somewhere, and I largely agree: career politicians are one of the major cancers on our political system. Instead of viewing politics as a public service, people try to make a career out of it. So, instead of voting how they actually feel on any given issue, a career politician votes solely to ensure their own job security. A lot of potential progress gets thrown out the window in this way.
I guess it boils down to the trifecta of Career Politicians/Campaign Finance/Lobbyists. An opposition completely unwilling to engage in the lawmaking process and our piss-poor media just exacerbate things.