I dont think this will account for it, be I do think a small part of it, is to do with people viewing formal BBC employees who sold out for the big cheque, possibly leavnig shows they present on TV looking for new presenters, in a negative light. The public support that Christine and Adrine enjoyed via the One Show, may have been lost the moment they signed for ITV.
Easier to like Christine when she is an attractive young irish woman, on her first big break, less easier when she has sold out a show you like, for a