You have Inside and Outside Organization and you can even enable that only (outside) contacts receive an OOF reply.
I would like a little bit more control over that, for instance by by white or blacklisting (external) contacts, so that they will or will not receive an OOF reply.
Also the ability sending an OOF reply for external addresses only when you do not have them as a contact. It's reasonable to assume that contacts might know you are away, or you just don't want to bother them. Also, this gives users the ability to prevent sending OOFs to mailingslist etc..