Power
You might perform the most powerful performance of Swanilda in Coppelia that the world has ever seen, but you probably won't have much power. If you're a high-profile soloist, you can boss around chorus newbies and make some really fussy demands for your dressing room—"temperature set to 19.25 degrees Celsius; I'd say 'please' and 'thank you,' but it'd be disingenuous"—but that's about it.
Ballerinas, by definition, dance someone else's choreography to someone else's musical composition. The most successful ballerinas know how to take criticism and not give too much feedback.
They're the ones who shut up and dance. Because they all know that whether you're a world-famous prima or a fresh-faced upstart, you've gotta work with the more power-heavy directors and coaches and composers and choreographers. You won't get far with defiance in this racket.