I think people are taking this the wrong way. “he is essentially useless as a power tool." I’ve seen people say that Jensen said that Cas was completely useless to them now, and he was only a tool. But that’s not what he’s saying here. He is just saying, dude lost his mojo therefore he can’t do the big powerful smiting shit and transporting shit that he used to do. Aka can’t be used as a power tool anymore.