Because its not a new micro transaction. You wouldn't actually purchase anything with NFTs that would be owned by a company like SE, you would be purchasing a license that would grant you access to whatever the NFT is tied to for that value, which would determine the price of the thing you actually want to buy.
An example would be buying something from the mog shop for 15$. That is a hard value item allotment that can only change at the discretion of the mog shop.
What an NFT would do is determine the price of the item based on the value of the NFT. If the NFT isn't worth anything that 15$ item could range from 15$ up to lets say 30$, because the value of the NFT is low. So in order for the price of the NFT to increase you have to invest more by buying more NFTs in order for the price to come down, but that devalues that cost of the NFT so the mog station would then buy back the value of the NFT at a lower cost to increase scarcity and drive the value of the NFT back up, which is what you would do by having to spend the NFT that you bought at a higher price. So you end up paying more to support the NFTs value, while the value of the NFT is controlled by SE, who buy it back for less than what you spent/invested.
So when it comes to video games you have to remember you don't own any of the digital product sitting on your hard drive, and even if you buy hard copies all you did was spend money on whatever packaging it came in. The digital rights management of video games, in this instance FFXIV, is an applied access license that you have to purchase a license to use.
There are already games in the "Metaverse" that use NFTs and a majority of them have a negative return of higher than the initial value invested, and for some its up to 250%. NFTs are just another way for companies to artificially gate the "content" they produce with another paywall and license structure so that you have to give them more money.