The simple truth is that success in any creative field is based more on chance and mass appeal than any creative merit. For every JK Rowling there are hundreds of published novelists who barely make a living, and thousands who a publisher wouldn't even take a chance on.
If you're in it for the passion, you'll do it whether you make money or not. Big successes are an anomaly, regardless of which mechanism the industry chooses to split up the loot. (Always in the favor of the publisher/label/whatever.)
If we want to encourage creativity, UBI is a better deal than worrying overmuch about trying to shoehorn creativity into revenue models. Because then at least the extra money, however much, would be extra on top instead of wholly inadequate.
