The main issue of this would be public defamation, i.e. wrongfully portraying someone as porn actor which might destroy their career. You cant really do that with written or drawn fiction.
But for that the pictures would have to be photorealistic, which is not the case just yet. But the tech is going to improve plus the generated images could be further manipulated (i.e. add blur/noise to the image to make it look like a bad phone picture).