I don’t want to drink the swill that many airlines serve on board, and would love an option to pay for something nicer. I’m not sure it would work, though, as a business proposition because of the cost to source a niche product, taking up scarce galley space, when the market for this might be limited.
Airlines might also worry that a paid upcharge in a premium cabin might cheapen the experience. On the other hand they don’t seem to worry that serving cheap wines cheapens the experience! So perhaps they should give it a go as a test to improve the product while generating incremental revenue as well?