I think you just answered your own question. The fair use argument is a lot stronger for something that's culturally iconic (and it means no-one's going to mistake the remix for an original work), and we have a lot more sympathy for someone who just wants recognition for their work than for someone trying to maximize their profits.

Looking at this case, it really doesn't look like she did much of anything. They are not a new medium and seem quite like a small alteration. If it was a painting of the final origami then I would be all for the defense (change in medium always struck me as good enough), but it isn't.

The whole kerfuffle was with the cover art, which was not licensed, and Jay Meisel has said the he would not license. It's unclear if he would have prevailed in court, but that was potentially far more expensive for both parties than the settlement that wound up happening.

They are? I'm not. It's pretty clear fair use to me - you can't fold the painting, it's not intended for that.