Absolutely no idea why they did any of this
She looks absolutely fine so they didn't need to Photoshop her (she hasn't got cancer in her strawberry floating hands either). Obviously William decided to edit the photo and caused the furore. What you do in that situation is not close ranks and give oxygen to the conspiracy - you post a picture of Wills and Kate beside a computer with a Photoshop 101 tutorial on screen and have a little joke about it, and there's no story anymore. Instead she's had to out herself as having cancer and everyone thinks her husband's getting buttfucked by the woman next door.