It's not to everyone's taste, for sure. I don't think anyone watches a quiz show deliberately for the "thickos", but all the same it's nice to have moments in a quiz show where you get it right and the contestant(s) get it wrong, and if that happens often enough then it helps lift the entertainment a bit. There's also a bit of variety involved, too. University Challenge is, mostly, contested by people at or near the top of the quizzing world, ditto Only Connect -- and Fifteen to One at least was fairly similar in its day, with some who are now among the world's best at trivia appearing in the show. If every quiz show were the same, contested only by the top quizzers, I think the public would in general get tired of being reminded how much better other people are at it than they are.
I guess what I'm saying is that the "thick people" are performing a national service.