As others have said, the lack of variety with the actors has been hindering this event. Even if Radcliffe and Watson have distanced themselves from the franchise, there's still other "big" names you can get. I'm sure the four main Fantastic Beasts actors wouldn't be terribly hard to get, especially if a revamped event happens closer to the third movie in two years. That's easy cross promotion for WB right there. Hell, get Johnny Depp; he needs the money right now