They seem to think that it's building the suspense up by only announcing one celebrity a day at a time. I don't actually care who is in it but I get irrationally annoyed when I see another 'news' item declaring the latest celebrity to be announce. It really is not a big deal.
It's a Saturday evening light entertainment show. And as that it's fine - the kids like it, and I quite like having a family show to watch all together. But they can fuck off with this over the top build up to a bit of fluff on telly.