A badly photoshopped photo was released and it was not only spotted but was bad enough that the photo/news agencies pulled it because of the obvious photoshopping. Someone fucked up, whether Kate (who isn't a professional so shouldn't be expected to be amazing at photoshop and know all the rules) or somebody at KP who is more professional, presumably.
I think it's perfectly understandable why she didn't want a photo taken, but in the U.K. what has caused the problem was the photoshopping of the image. In the US of course, and online, it was way over the top speculation that exploded with the photoshopped image.
It's not fair that she had to come out and make a statement whilst undergoing chemo, just like it's not fair that she had to be photographed and filmed leaving hospital postpartum. Nobody wants to do that!
Sadly for her in this instance she doesn't have the freedom to be invisible. That's the price she and her family pays for the lives they lead. It's a very heavy price in my opinion, and it's not the sort of price you or I would have to pay were we to have chemo. But the truth is that serious illness makes the bad things in life even worse. People lose jobs, lose friends, women often lose husbands and life partners, small business owners struggle immensely, and single people with no relatives are often extremely isolated. So it's not fair, I wouldn't want it, but in a way it's no different for her than for anybody else. Her vulnerability isn't financial, it doesn't seem to be family support, it's public life and the media. Most people have an area of life that's problematic when dealing with cancer, and that's alongside the cancer (or illness).
I feel sorry for her just like I feel sorry for my friend living in the highlands who needs chemo and radiation, not preventative, who needs to leave her home for four weeks to get treated, to stay in a supported B&B because she has nobody to drive her to and from appointments.
I wish them and everybody dealing with a frightening diagnosis and treatment a recovery as pain free as possible.