So that you can run an AI company, churn out enough material to flood a particular market, and leverage copyright protection to cash in. Like say you call it the Kittenator, and then do automated keyword search for anything involving kittens - kitten in a box, kitten wearing socks, kittens on the rocks, kitten versus fox - and generate 25 different images for any given keyword combination, and push them out to major image-sharing platforms. The stock imagery market is pretty large but if you have the copyright enforcement in your pocket you can go after it in chunks.
The court did not say AI generated images are not eligible for copyright. They said machines cannot be assigned copyrights. That’s because only humans are eligible.
If you are a human who creatively uses a tool to generate something, you’d get copyright protection.