One question, why people always say that disabling passwords is important. AFAIK, passwords with keys is better than keys only. Now if someone gets the keys they can access the service with those keys without the passwords. Disabling passwords just makes security in one way worse. Think about chip & pin, because you have your credit card, wouldn't it be smart to disable PIN completely? Of course key ring could be enc…
Disabling password-only authentication doesn't prevent you from using a password on your key. When you login with key-based authentication you will be prompted for the password for your key, even if password authentication is disabled, because they are two separate & unrelated processes.