I think that's the Carol Vorderman factor at play there, Nikki. Both her and Kapalinsky are so ubiquitous with their face of the brands and celebrity dancing competitions it's like you can't switch your TV on without seeing either one of them sometimes.
The British public seem quite demanding of their newsreaders, and once you've thrown a bit of celebrity into the mix, people start getting mildly irritated. I totally accept Kaplinsky as a smart journalistic choice for Five, she has undoubted cred, but she's on so many other programmes it dilutes their investment somewhat.