The Palace just spark speculation like this with their secretive statements though.
If they'd just said something fairly cover all about each of these things, people would just say oh well, and move on with their lives. I don't know, (and I really don't know!) something like Kate is out for 3 months for a hysterectomy due to endometriosis. William can't come this morning because he has a minor illness/George has broken his arm playing rugby/whatever. People would just think 'ah well, these things happen' and move on!
There hasn't been half as much speculation over Charles.