Thunderbird recently added the option to hide Local Folders, which was great for those who never used them. I think it would be just as useful to have an option to hide the default Personal Address Book and Collected Addresses.
If someone is syncing contacts via CardDAV, they probably don’t need these default address books, yet they still show up in the Address Book tab all the time.
Also, if this feature gets implemented, it would make sense to hide the All Address Books when there’s only one visible address book. That way, the UI stays clean and clutter-free.