This is an important debate to keep having. I personally believe there is an unethical component to training without notice/compensation to the content creators. We've basically created a new way to copy by synthesizing new images using unwitting ML "art teachers." Without them it all becomes impossible. But possibly more disturbing is the potential to use AI for unethical purposes in the form of Deep Fakes which can be used for extortion and propaganda as well as to wrongfully convict innocent people or get guilty people acquitted.