It's a reminder that no matter how well trained a pilot may be, when he/she is spatially disoriented (as the AirAsia FO apparently was), anything can happen.
So what disoriented the AirAsia FO? It appears to have been the high roll rates he encountered and the unnoticed entry into the initial bank. If those had not happened and he had started flying using the controls gently, then in all likelihood, nothing untoward would have happened. Those are all things that can be fixed in the transition to Alternate Law.