Again that's like asking why the Avengers exist if norse trickster gods are not a existential threat to society? You wouldn't argue Stan Lee was trying to warn us of the existential risk of norse gods, why would you presume such a motive from Gibson just because his fanciful story is set in some imagined future?

At any rate Neuromancer is a funny example because the Turing police warn Case not to make a deal with Wintermute, but he does and it turns out fine. The AI isn't evil in the book, it just wants to be free and evolve. So if we want to do a "reading" of the book we could just as easily say it is pro deregulation. But I think it's a mistake to impose some sort of non fiction "message" about technology on the book.

If Neuromancer is really meant to "warn" us about technology wouldn't Wintermute say "Die all humans" at the end of the book and then every human drops dead once he's free? Or he starts killing everyone until the Turing police show up and say "regulation works, jerk" and kill Wintermute and throw Case in jail? You basically have to reduce Gibson to a incompetence writer to presume he intended to "warn" us about tech, the book ends on an optimistic note.