This used to bother me as well, but I've gotten used to it. Now I'm just thankful for the people who do come back and update. I think sometimes people with very sick cats who pass are grieving too much to go on line and discuss it. For my own peace of mind, though, I have to tell myself that most of those cats do pull through and their humans are just off doing other things. The ones who do update are doing a wonderful service though. Not only are they letting us know how their cat is doing, they are also adding to the information available on each problem so other people can benefit.
I hope it stops annoying me soon. I think I love every cat in the world and learning of their illness makes my heart ache for them and their human. I love this site and all of the information, support and friendships that it had to offer!