I think generating and selling images of any kind is not a problem in itself. There might be legit use cases. eg, every World War II game is in essence a carousel of CGI depicting a war that happened, complete with actual events and historical figures, sometimes adding wild distortions of alternative developments.
What why need is to enforce standards and social norms to make sure that those images (or sound clips, or texts, or videos) always carry a footer and/or watermark, plus separate metadata, clearly indicating that they are CG. Let's make it unthinkable for a news outlet (or an individual) to use those images hiding the fact that they are not “real”.