With that in mind we can return to the original point of this discussion: should authors respond to reviews? If they want to, yes. The problem with author responses in the blogosphere isn't so much that bloggers don't want authors to respond, it is that some of us have had bad experiences with it and would rather you keep out of it if you're unable to act in a manner that is becoming of an author (a great example of a horrible situation can be found here). Not all of us can be Harlan Ellison who, let's be frank here, gets away with behavior that most people couldn't get away with if their lives depended on it--a fact, I suspect, has something to do with a strange fascination people have with a man who is not at all afraid to say whatever the hell he wants.
Authors should consider how they are going to respond to a review or a discussion of their work. Bloggers are not at all against the idea of an author coming in to get a better understanding of a particular point, and if your intention is to understand the criticism in order to improve your writing, there is no contention with that either. But if your intention is to argue with a blogger, that's where the problems arise. Nobody wants to have to deal with an author who can't accept that an individual's opinion is their own. We don't want to hear why we're wrong in our review and why clearly we didn't get what you were trying to do. All of that is irrelevant, because we all have unique reading experiences.
As an author, you need to ask yourself a question: Is sacrificing your career worth it in order to argue with a reviewer over some point they made? And if your intention is not to argue, but to understand, a good way to go about this would to be preface your questions with that information. Bloggers are not going to universally pan you for trying to get a better understanding of the criticism lobbed at your work. In fact, they may even praise you for trying to be active in the reviewing community, particularly because that tells them that their opinions actually matter to you, that you give a crap what they think, and that you may, in fact, take much of what they have said to heart for your next work of fiction. But be conscious of the consequences of argumentation in the blogosphere, because what you do online can and does have an affect on you as a professional. You will be looked down upon if you act childishly, and for good reason.
What do you all think about this? If you've written blog posts about it, let me know in the comments.
P.S.: Some other instances can be found here and here.