It is cheaper, and more private, so why spam the blockchain, when there is a better way with no spam?
There is orders of magnitude difference between "why spam the blockchain, when there are more effective ways" and "stop spamming the blockchain, it does us harm". Of course and there are less expensive solutions to have NFTs on-chain, but you (or at least, the Bitcoin protocol) don't ever force somebody do something for
their good. There is also a less inefficient manner to burn coins; yet people send them to 1111111111111111111114oLvT2. Hell, a great percentage of the Bitcoin userbase still uses Legacy addresses.
@BlackHatCoiner raises good points but we should draw the line between being censorship resistant and having no limits and allowing everything. As a matter of fact, Bitcoin is filled with limitations.
I'm not suggesting that we should disable every single limit most clients have by default, but I'm just curious to know when we consented that line. Because as far as I know, developers drew a line in non-standardness and users followed later on without much debate. For example, what's the explanation behind the limit of OP_RETURN at 80 bytes by default?
Furthermore, standardness being what safeguards the system is flawed in the first place. Consensus rules protect from whatever. There's nothing stopping a group of miners from setting up a market, or just sharing their node URI, with NFT users, wherein they bypass the non-standard rule of dumping transactions with Ordinals etc., normally having their transactions included into blocks. And that's even worse, because now regular users don't see how much filled the mempool is, and the fee they select will not correspond accurately.
In fact there is pretty much only incentive for miners to disable most non-standard rules.
Sure, the blockchain doesn't care, but in a maximally free situation, the NFT people would 'win' in the sense that it may only be worth paying high transaction fees (due to high demand for these JPEGs) to send around either expensive NFTs or large Bitcoin transactions. It may not be worth it / profitable anymore to use Bitcoin as an everyday currency.
If there is demand for expensive NFT transactions, shouldn't the users have the freedom to make them?