Many artists do not want to do commissions. In fact, you could argue that people who want commissions are very selfish. Not only do they want to force artists to work on their thing, often driven by vanity, they even want to own the copyrights to the work!

NFT buyers are clearly more respectful of an artists craft: They buy the work the artist really wanted to create, and they respect the fact that they cannot be the owner of the work in a moral sense.