As someone who likes NFTs in theory, the "it's just a url" problem is a real stumbling block for me, because it's a point of fragility for the asset.
If the NFT is just a URL, and there's nothing within the NFT itself that provably links it to a specific work of media, and ideally a signature from the original artist, then there's no way to be absolutely certain that the piece of media currently vended by the URL is in fact the same piece of media vended 10 years ago when it was minted. You could have a situation where people mint NFTs as "shell art" that they trade back and forth to create some kind of established history of value, and then stick in some new piece of art at a later date with a false history of value. Or the URL host could go under or get corrupted by bad actors and start vending the wrong data, and still, you'd have no way to prove what the original digital media was.
That's honestly a blocker for me.
Now, if the NFT actually included a hash of the media AND a digital signature of the artist that could be externally verified, then I might be interested.