Why should anyone care about a bipartisan government? Why care about the appearances of "playing along" more than achieving policy goals that actually help people?

Because that's how it's supposed to work. The alternative is a one-party government -- fascism, in a word. Look it up.

People's beliefs are what they are, probably helped along by a media that has held up bipartisanship as some kind of ideal. You can't change those beliefs in an election cycle - you take them as given and do your best to meet them where they are.