Anything else is going to bite US in the ass. Asking for consent kills any kind of open source development. It puts AI solely in the hands of like three companies. Our economy is going to be very AI focused in the future, they would literally own all of us.
You aren't getting paid either way so we might as well all enjoy the fruits of humanities labor freely instead of been forced into a subscription model of it.
Making llms requires a stupid amount of data, much more than what is found in the creative commons. Same goes for image gen. Unless you have been accumulating data since forever through tricking people when they sign up to your website or app, you can't train anything without scraping most of the data.
It has nothing to do with licensing but the fact that there just isn't enough "free-use" data.