Mermaid,
I think W. wants to extend this to his girlfriend too. However, in public perception, she's not a Princess yet so that warning didn't extend to her and it's sort of a test in how she'll be able to handle the press.
The royal family issued a notice about being photographed at Christmas but I didn't hear about one being issued by the Middletons. Maybe if they had, and asked for privacy and respect, it would be different.
If someone went onto private property and pressed their lens against the glass to take photos of Christmas lunch, that would be one thing, but how were they taking photos of lunch through the windows and this was so bad, if they were always on public property? Maybe they shouldn't have had lunch by the window if it's that easy to photograph, or, if its long lens, which I do think is sort of different...how were they to know they'd be sued over it? In their minds, they were doing their job and got some good photos, and might make money off of them, and then they get hit with an injunction. So the stake-out was a waste of time, which I'm sure doesn't hurt them, but I don't think they had notice beforehand.
I think it will be a fine line, in courting the press and respecting their work, and also keeping healthy boundaries up. I agree that the more that can be done to keep up boundaries or make new ones, is good. If they are reassured by a "coming out" now and then, that should be enough. But I mentioned the tree thing because for some people, it's really that important, that someone they admire so much, is accessible to them and they might even climb a tree to get their attention. Even papparazi. Let's just hope no one gets the idea to climb a tree and enter in through a bedroom window. !