John wick is supposed to be a shallow character. A nobody who is surprisingly a goat assassin. The surprising simplicity of the first movie is exactly what it's supposed to be. Man mad cuz wife dead and brat crimelord son kills dog gets revenge.
Just like another Keanu movie that there shouldn't have been sequels to the story suffers if the perspective gets expanded. Prison break too, forcing follow ups means the story gets more complex whilst the simplicity is it's main draw.
Keanu sommes un those roles a he is a bit aloof and emotionally detached. Somehow that suits both roles, but there isn't much there to flesh out a longer story.