Why?/How does that relate to my answer? It'd make it harder to just accept a changed key instead of leaving the decision to the user, and would make use cases where the user doesn't want/need to authenticate the server harder (one can probably debate each scenario for that if the decision to not authenticate was "right"). Although I find it a bit weird there's not even an option to pass a host key to SSH instead of editing the KnownHosts file.