Because when I buy a piece of art, I can hang it on my wall and look at it.
If I buy an NFT, it doesn't give me the right to print a picture of the art and hang it on the wall. I have no rights to display the picture of which I own the NFT. All I can say is that I own the NFT of that piece of art.
So, I can hang the hex code of the NFT on my wall and look at that I suppose. But the actual piece of artwork that is associated with that NFT? I can't even display it on a digital display in my house, because that's copyright violation.
Many NFT platforms attach legal terms that explicitly allow you to print or otherwise display the media for NFTs you own, artists generally grant permission for it or consider it a social convention that it is allowed.
If I buy an NFT, it doesn't give me the right to print a picture of the art and hang it on the wall. I have no rights to display the picture of which I own the NFT. All I can say is that I own the NFT of that piece of art.
So, I can hang the hex code of the NFT on my wall and look at that I suppose. But the actual piece of artwork that is associated with that NFT? I can't even display it on a digital display in my house, because that's copyright violation.