You're just not being imaginative enough. An example just off the top of my head is a game where you have to fight a medusa by relying on shadows/reflections o

You're just not being imaginative enough. An example just off the top of my head is a game where you have to fight a medusa by relying on shadows/reflections only because if you look at it directly, you're literally petrified. Attempting to do that without proper ray tracing simply wouldn't be good enough.