One key benefit is that passwords or keys are sent across the network as infrequently as possible with Kerberos. With SSH either passwords are being transmitted or you are persisting files with secret keys, both of which have concerns for security. This article does a great job comparing and contrasting SSH and Kerberos: http://docstore.mik.ua/orelly/networking_2ndEd/ssh/ch11_04.htm
"When a user identifies herself to the Kerberos system, the identifying program (kinit) uses her password for an exchange with the KDC, then immediately erases it, never having sent it over the network in any form nor stored it on disk."