This is all kind of pointless for my silly personal blog, so you could view it as a symbolic way of registering my displeasure with StartCom ;-) To answer your

This is all kind of pointless for my silly personal blog, so you could view it as a symbolic way of registering my displeasure with StartCom ;-) To answer your question, suppose I think my key has been compromised. Then I don’t want to continue using that key because non-MITM’ed communication between my server and the client is compromised. So I generate a new key, and I’d like a a new certificate for that new key—the old one won’t work (Apple Secure Transport bug notwithstanding). My users are still vulnerable to a MITM attack, yes. --edit: assuming that the user’s connection uses a non-PFS cipher suite.