What you say makes perfect sense Bob, especially for users of the free version... but if Avast is serious about retaining paying customers, it's worth considering that for the most part, people don't decide to part company with their cash for reasons that make sense.

Example: When GM bought SAAB, they knew that some people will keep buying SAABs because of their particular quirks, like having the ignition key on the floor, so even though having it there no longer served it's original purpose, they didn't move it.
So many people have told me how they miss the voice/popup announcement. Yes, it no longer serves its original purpose but for them it's a nerdy talking point - their computer suddenly announces the update out loud. They see it as part of the Avast "brand".
They may choose to renew or not renew their AIS licenses for any number of reasons. I for one, am not in favour of unnecessarily giving them another reason not to.