If you can just ask the LLM to give you the contents of my book you are less likely to buy it, and if you can just ask the image generator to generate an image in my unique style for free you won't want to buy my artwork.
I think it makes perfect sense that a model needs a specific license to train on my work, especially if the model is run by a massive corporation making a profit off it, and the model after downloading a copy of my work and "training" can reproduce it verbatim on request.