Could be: a lot of the 'branding' of the actor these days is about curating what films they show up in. Like, if Johnny Depp is in a movie, you know generally what kind of film it'll be. The AA (Artificial Actor, haha) would benefit from having an agent, much like real actors, to keep consumers' meta-dissonance down.

That said, actors swap between wildly disparate roles all the time and no one seems to care!