You've got two groups in power, each of whose members want to game the system for personal gain while making token efforts to satisfy the demands of the people in order to keep on getting the opportunity to do that. They've both got a vested interest in keeping things running, and in doing what their particular slice of the public says they want done, but that's the limit of their altruism. Recently, however, the Republicans elected a batch of people who're more interested in crashing the system than gaming it, largely out of frustration with the degree to which it's been exploited. This is the most charitable I can be about the whole thing.
EDIT: Before, keeping things running took precedence over bowing to public whims for both parties, because the important thing always was the gravy train. What I mean by "interested in crashing the system" is, you're stuck in a situation where a large part of the Republican votes want to force sweeping changes that they think will fix everything no matter how complex it really is, and the only alternative in their eyes is to break it all if they don't get their way. As far as they're concerned, it's not worth having a government if it's not the one they want. And a lot of those changes will likely break the economy anyway, so there's no good outcome.
It's a stupid response, but it's to a very real problem of corruption. Rejecting compromise is, admittedly, a rejection of one of the major contributions that allowed that problem to exist in the first place, and it's definitely emotionally satisfying, but it's the worst possible way to go if your goal is to actually make things better. It's been a long time since we've had politicians so invested in their principles that they take priority over maintenance of the status quo. It's just that they also take priority over the welfare of their constituents.