Michael, thoughtful comments as always!
As someone who gives and gets criticism regularly, a few comments:
I do think criticism (and even the 'threat' of criticism) can be very helpful. For example, for us, since we have a forum for thousands of people across the industry, it forces us to be sharper and more critical of ourselves before we publish because we know if we do not we will get hammered in the comments.
Also, I like getting specific, concrete criticisms. For example, am currently having an email exchange with a member who said in a survey response we should be more positive. I think he is right and we are discussing what more positive topics we should cover.
Bad criticisms are like the image above or things like IPVM does it for 'blogging clicks'. Criticism without substance is effectively low class disparagement.