Callbook

[VK2AZ]

A genuine question - given I have pretty much always had things like the callsign database and QRZ.com available since I have been licenced, I do not see the purpose of a callbook.

What am I missing?

I don't think you are missing anything.
A hard copy callbook is not the best idea in my opinion, but a searchable online database, as a single source of truth, would be a good idea.
You could also export it as a PDF for those that wanted it.

Unfortunately, I don't think this is ever going to be possible.
The current new ACMA callsign database is not very useful.

Even if you used the data from that database, you would have to rely on everyone voluntarily going to a site and updating their own information.
Experience tells us that this is never going to happen.