I think the bad part of it is stripping consent from the original creators, after they published their work. I personally see it as an unfortunate side-effect of change. The artists of the future can create with AI already in mind, but this was not the privilege of the current, and previous generations.

Getting back to "learning from", I think the issue is not the learning part, but the recreation part. AI can churn content to orders of magnitude higher than before, even in the age of Fiverr and other tools-opportunities. This changes the dynamics of the interaction, because previously, it took someone tens of hours to create something, now it takes AI minutes. That is not participating in the same playing field, it's absolutely dominating it, completely changing it. That is something to have feelings about, especially if one's livelihood is also impacted. Data is not destroyed, and neither is its ownership, but people don't usually want the exact thing, they are content with a good enough thing, and this takes away a lot of power from the artists, whose work is the lifeblood of artistic AI in the first place.

So I don't think it's as nonsense as you state it. But I do understand that it's not cut and dry the other way around either. Gatekeeping culture is definitely not a humane thing to do. Culture comes and goes, intermingles, inspires and changes all the time, and people take from it and add to it all the time. Preserving copyright perfectly would neuter it, and slant the landscape even more towards the already powerful.