A good bit different from the Hebrew literary prophets, isn't it? Sure, they do address the rulers, but not to legitimate them! They rebuke them for their treatment of the poor and marginalized and for their worship of other deities. And they warn of the coming doom unless the change their hearts and lifestyles.
You do see prophets, like Nathan, who legitimate David's dynasty. But Nathan was also the one who confronted David about Bathsheba and Uriah! Don't try that in Assyria if you want to live.