why not option to automatically add pub key?

[Neal Becker]

One of the annoyances of ssh is the need to transfer the public key from
client machine to server machine, and append to authorized_keys.  Although
it's simple to do, it's annoying to have to do this manually.  Why can't
this be automated?  ssh offers to add new machine to known_hosts.  Why
doesn't it offer to add the public key to authorized_keys?