It would have been better if we had started out the history of films by never using the same actor more than once.
For a lot of films it’s more about watching Brad Pitt, Tom Cruise, Jennifer Anniston etc. play a new character with the focus on them instead of seeing a fresh unknown face and the focus on that character’s personality.
I wouldn’t mind a world where once you were in one movie you were never cast again. It would make movies more unique and mysterious. Personally, I like Indie films with unknown actors more than many Hollywood mainstream movies with recycled actors.
I will concede that an amateur actor would probably not have crushed the role of Daniel Plainview in “There Will Be Blood” like Daniel Day Lewis did. But that is an exception where the actor disappeared into the role and I never thought I was watching an A list actor. The majority of actors don’t disappear into the role.
Also, a bonus to never using the same actor is that more people would be able to be in a film at least once.
The thing is, most actors do only average about 2 movies a year. On a particularly busy year they might have 3. Marvel have thrown off the equation a bit because the same character will show up for small roles in multiple movies but it’s pretty rare otherwise to see an actor consistently do more than 2 movies every year.
I like the idea of more diverse casting but we (the moviegoing public) broadly won’t go and see the movie unless it’s someone we know.