Those are fair points, but my understanding is that it's not specific to NFTs iteself:
- buyers not knowing exactly what they buy is something that happens all the time in the real world. That doesn't make it right, of course, but that doesn't make all those sales "non-deductible donations".
- artists already use a lot the same kind of mechanism used for NFTs. For example, limited editions of a reproduction of a piece of art. You won't own the original piece, but you will have a copy, with a certificate that proves its authenticity. Part of the price is usually a high quality reproduction, but an often significant part is the certificate and the scarcity of the item.
I think my point is that "limited" NFTs as in "multiple NFTs for one piece of art" are something already natural and established in the art world. I agree with you that "unique" NFTs as in "one NFT for one piece of art" are more confusing and already somewhat existed before in the form of copyright holding. One difference that I can think of is that with NFTs artists can keep the copyright and thus control over how their art is used, while still allowing people to "own" and speculate on the art itself.
All of that is just about the NFT concept by itself. There is also the implementation part (crypto), how it's used, and arguments like "is it even a good idea to do artificial scarcity in the first place?". I don't know enough about those subjects to have an opinion on them.