It's strange how shallow characters can be popular because of "cool" factor huh? I guess it's no different from a female chracter being popular just because she's hot.
This new God of War has reinvented Kratos. Now he is actually interesting as a character, a depressed and tormented father with a checkered and secretive past, who was initially reluctant to be drawn into any action or confrontation. That is called character depth. In term of storytelling, the reluctant, retired hero who was forced into action is always more interesting than the "I am looking for a fight because I am such a badass" protagonist, (whose shallowness seems to appeal to only young male gamers.)
Anyway, they seemed to have made all the right choices with the new game. It basically is the tonal opposite if the other games in the franchise. I think games like this showcase how developers and storytelling have only evolved.