It's useful for hitting certain philosophers with. Canonical examples: moral realists sceptical of the potential power of AI.
There are philosophers who believe that any superintelligence will inevitably converge to some true code of morality, and that superintelligence is controllable? Who?
Just a minor thought connected with the orthogonality thesis: if you claim that any superintelligence will inevitably converge to some true code of morality, then you are also claiming that no measures can be taken by its creators to prevent this convergence. In other words, the superintelligence will be uncontrollable.