Actually, I think we learn a lot about the candidates over time. I think a couple of them should have dropped out earlier so the debates could have been more focused, but on the whole, this exposure does show you a lot about the candidate over the long haul.
I guess it’s easier than the 19th century, when they called campaign speeches “stump speeches” because the candidates were literally standing on a tree stump to address the voters.
We could learn more but we don’t. For the candidates these are campaign appearances (the same ‘stump speeches’ over and over), for the moderators they are spectacles to entertain us.
In the nineteenth century ‘the media’ consisted of someone you knew who knew someone who knew someone who knew someone who knew someone who knew the candidate- I can see where that media could be more conducive to thoughtful judgement.