It is morally right to be able to use others' copyrighted material without permission. For analysis, criticism, research, satire, parody and artistic expression like literature, art, and music, In the US, fair use balances the interests of copyright holders with the public’s right to access and use information. There are rights people can maintain over their work, and the rights they do not maintain have always been to the benefit of self-expression and discussion. It would be awful for everyone if IP holders could take down any review, reverse engineering, or indexes they didn’t like. That would be the dream of every corporation, bully, troll, or wannabe autocrat. It really shouldn’t be legislated.
AI training isn’t only for mega-corporations. After we've gone through and gutted all of our rights and protections like too many people want to do, we'll have handed corporations a monopoly of a public technology by making it prohibitively expensive to for us to keep developing our own models. Mega corporations will still have all their datasets, and the money to buy more. They might just make users sign predatory ToS too, allowing them exclusive access to user data, effectively selling our own data back to us. People who could have had access to a corporate-independent tool for creativity, education, entertainment, and social mobility would instead be worse off with fewer resources and rights than they started with.
I recommend reading this article by Kit Walsh, a senior staff attorney at the EFF if you haven't already. The EFF is a digital rights group who most recently won a historic case: border guards now need a warrant to search your phone.
You should also read this open letter by artists that have been using generative AI for years, some for decades. I'd like to hear your thoughts.