What do you expect to happen when an upgrade to a daemon involves a policy choice?

For example, let's say that you have Postfix using a smarthost as a relay, and the new version of Postfix requires relays to have a shared secret for authentication with each of their trusted clients. That isn't something that can be handled by an automated config translator.

This sort of thing happens a lot. The best that can be done is putting the changes into a document for you to read, understand, and then make decisions.