Why doesn't Apple come out with an OEM indestructible case for the Iphone?

Seems like if anyone should know how to safe guard this phone it’s Apple, so why do they leave this to a cottage industry? Are they making so much money that this class of peripherals is just right below their sense of class?

Maybe they want us to destroy them so we’ll buy more? Maybe they think their crazy insurance deal is good enough? What do you think?