Seems like the American public have either been worn down into non-engagement or radicalised, and I think it's a combination of the designs of politicians (the partisan game is simpler to play and costs less and is more predictable than the one that is focused on societal progress) and that a lot of people would rather believe that the only thing between us and a better society is the evil 50 senators in the other party. Distracts them from having to take personal responsibility for their contribution (or lack thereof) to society and that many of our problems don't have obvious legislative solutions.