Indeed, and I agree that Adobe is in the wrong here. For an agreement between Adobe and an artist to be truly permissive, the artist should have the ability to not give their consent. Ethically, I think Adobe is in the same position as the other AI companies – if the artist doesn't directly (EULAs are not direct, in my opinion) agree to the terms, and if they don't have the option to decline, then it isn't an agreement, it is an method of coercion. If an artist, like you said, doesn't want to be paid micropennies, they shouldn't have to agree.

I believe it is completely reasonable for an artist to want to share their work publicly on the Internet without fear of it being appropriated, and I wish there was a pragmatic way they could achieve this.