The only real problem with them is that they are conceptually simple. It's always just a subject in the center, a setting and some modifiers. It's doesn't produce complex Renaissance paintings with dozens of characters or a graphic novel telling a story. But that seems more an issue of the short text descriptions it gets, than a fundamental limit in the AI.
As for the AI-typical image artifacts, I don't see that as an issue. Think of it like upscaling an image. If you upscale it too much, you'll see the pixels. In this case you see the AI struggling to produce the necessary level of detail. Scale the image down a bit an all the artifacts go away. It's really no different then taking a real painting done by a human and getting close enough to see the brush strokes. The illusion will fall apart just the same.