I think this probably explains much of it. Aladdin was a pre-sold concept based on a beloved animated film. They could have cast almost anyone in the role and it would have made a similar amount of money. Massoud did not really do anything to contribute to the success of the film; he just had to go through the motions of the established character and not completely screw it up. There was not a lot of potential to show any "acting" here, and I don't imagine many people bought tickets because of the presence of Massoud vs. it being the live action "Aladdin". For some other actors, I also think that some of it happens when they've made a few films in a style people like, then try to "stretch" into other types of films such as when comedians or action stars try and make serious dramas. Audiences tend to typecast actors, and when they stop doing roles that fit those expectations, a good share of the audience will stop attending their films. I'm not really sure how to explain Hemsworth. Audiences enjoy him as Thor, but don't seem to respond to him regardless of what other genre he appears in. He's made other sci-fi, thriller, action, drama, and comedy films, and none seem to really connect with audiences.