Part of it is, I think, because we're growing quickly -- even for the same problematic case percentage, there are going to be more in absolute number. (And, as Stripe becomes more prominent, the cases that happen will themselves get more attention.)
In addition, the cases that get public attention generally aren't clear-cut. For example, the other discussion on HN a few weeks ago was about a marijuana-related business that most likely violated our ToS.
We care a great deal about providing great support at scale. Each of these cases triggers a lot of internal discussion about how we might have been able to do things better.