I often program and write for pleasure. Both are skills I like to exercise. Often, but not always, I'll give the results of that hobby away for free.
But here comes Google, saying "We want a presumption that we can use all of your works -- whatever copyright license you choose -- to train our AI systems."
Just fuck off. You already use some of my software for free. Why when I say that this particular item of prose is for me, do you presume to want that too.
It's some sort of tech-bro colonialism.
(Don't give me any "But you can opt out" b.s. "Just like robots.txt" isn't a viable opt-out mechanism. The people who do metadata and rights professionally -- libraries and rights collection agencies -- don't use that mechanism, but link the metadata to the work via ISBNs and the like, or embed the metadata as seen by the copyright notice on every movie or the Dublin Core markup. How about we use a opt-in mechanism, a set of rights to make a copy, we could call it "copy right".)