Most people don't pay all that much attention to politics. When they take a moment every 4 years or so to do so, they take their cues from The Very Serious People who rule our discourse. And those Very Serious People tell people that personality and tribal connections are how candidates should be judged, like reality TV show contestants, instead of trying to communicate the idea that POTUS is a rather important job.
I recognize that inevitably a lot of politics is going to come down to those things. People who don't pay all that much attention to things are going to make their decisions based largely on personality. But the problem is that too many in our media help reinforce the idea that this is how decisions should be made.
