Nobody would ever think about Adobe or Nikon having copyright claims over your pictures. For me it's just a tool, the artistic part is providing a good description/base image, refining and choosing the best output.
Anyway, I'm not a lawyer and we probably live in different countries, so it'll be interesting to wait for the first lawsuit.
But it is illegal to share pictures of Eiffel Tower, for example.
People do it, but they shouldn't.
If I put a picture of Eiffel Tower at night in a book or any other kind of commercial product, I have to pay to use it. Doesn't matter that it's there for my eyes to see it.
The question is: are the images generated by an hyper accelerated learning machine using copyrighted material without the author's consent legal?
I think they shouldn't be and the data included in the training should be free or licensed.