I frequently write versions of this post, but it drives me nuts when apparently smart people are a bit too enamored with the reality TV aspect of our campaigns (though, admittedly, with the Donald in the mix that makes a bit more sense than usual). It isn't that the theater doesn't matter for either elections or for governing. Of course it does. It's just that too often it's portrayed as the thing that should matter, the only thing that does matter. Policy is just your choice of uniform, your set of accessories. Go team yellow spandex!
Again, of course it matters, some. And I think it should matter... some. When the issue is getting elected, even relatively high information voters are basing their choices (including whether to bother to vote) on not enough information, so the theater fills that in somewhat, if imperfectly. It provides clues to how someone will govern. One can't deny that the theater impacts popularity, and popularity does, to some degree, impact the ability to do the job in our silly system.
Still, the policies matter more...