Dolph Ziggler is one of the top heels in the WWE, but he isn't proving to be one of their top stars.
While having him fight against the heroes of the company is entertaining, he doesn't have the right chemistry needed to convince the audience or his superiors that he should be the man.
For someone whose persona deals with the idea of perfection, he just doesn't have it. At least, not as far as being WWE champion is concerned.
While Ziggler may have gotten runs as the United States Champion and the Intercontinental Champion, that is all he will ever be.