There's no such thing as objective moral and ethical good. To me, Mitnick is a hero deserving of the highest praise. He inspired myself and many others to get started in this world. It may be difficult to understand if you didn't come into computers in the late 80s/90s.
Anyway, I suppose you could make the case that Mitnick was taking on “the Man” which is more utilitarian, but that’s a bit anemic imo.