It's simple really, because it is a conversation and conversations by there very nature should be free ranging expressions of interest.
While I do believe that anonymity breeds irresponsibility, leave that up to the Blogger to decide. Some blogs might benefit from anonymous posts.
I have a real problem with any formal codes of conduct. And screw civility. I expect people to be very uncivil regarding some of my views. Some very useful conversations can be very uncivil.
But I do draw the line, no hate-speech, nothing nutty or abusive. And, I get to make the call in the context of the conversation.
Code of Conducts exist outside the context of the conversation. The conversation that takes place here, might be very different to that to takes place elsewhere. Why subject them to a common standard?
I also find it particularly concerning that we would somehow, someway subscribe to a group policing mentally in which a few could potentially get together "When we believe someone is unfairly attacking another, we take action.". This is deeply troubling. Who, for instance, gets to define the "believe" part of that? Sometimes it might be self-evident - such as the attacks on Kathy Sierra. I suspect most won't be. And the attacks on Kathy aren't a job for a bunch of self-appointed "blog vigilantes" - they are a job for the Police.
Blogs ultimately should be about transparency. We should revel in what they expose, not seek to limit or hide it. And lets leave the policing to the real police.