The problem isn't whether you should or shouldn't get the copyright, that's ultimately up to the producer of the NFT. The problem is the rights aren't being clearly communicated to the buyer upfront. Also, the terms of the NFT should be in the NFT itself, not hidden on a website.
Sellers and market placed greatly benefit from the unclear IP situation.
Though in the most "art" NFTs, e.g. not games, people are just tossing money around to show how rich they are, there is no interest for them in the art itself.