Greetings Kiran,
The problem with that is that when you are creating or changing the Notification, you may initially not know the proper Damage Code, much less the Cause Code. Then, SAP will not let you save the Notification. And even if you create a code such as "TBD" - To Be Determined, there is no check if you changed it later on to an actual code, when Technically Completing. Therefore, it may be beneficial to make this enhancement.