There are going to be a few cases where keys are lost or stolen. It may be possible to build multi-sig wallets that allow for you to migrate an identity to a new key. What we're looking for is some kind of statistical means of trying to reduce bad actors. Even if there was no recourse for you and you were totally screwed I'm not sure it totally invalidates the concept of having a key or a mechanism for trying to remove bad actors from social discourse. You could trip and die because you wore shoes. You could get locked out of your house... bad stuff does happen - it doesn't mean we shouldn't wear shoes or have keys.
