Yes, she probably is a much "better" or more compelling character than, say, Boba Fett. But that misses the point. There isn't likely a big enough market for her character to justify a movie, nor is there likely to be even if she were marketed to the general public. Disney has a pretty careful plan for Star Wars, and they aren't going to screw it up by making something that wouldn't have a market. The market is getting somewhat "saturated" by having a film every year or so, and I would expect that to continue through about 2025 or so. By then, I think people will be tired of Star Wars, unless the franchise takes on a new direction in the next trilogy that people find REALLY compelling. But otherwise, they will make a TON of money for the next 6-8 years, and then likely let it die down for awhile before doing anything new. And in terms of marketing strategy, they're golden by doing that. Again, they will have made a ton from the films themselves. They will also have had Star Wars lands up and running for awhile in their parks. The combination will have a whole new generation of Star Wars fans locked in and loving the franchise, which will sell merchandise pretty steadily for at least another decade beyond that. So, they don't need to take a risk on a character like Ahsoka for a film.