Add the Address book to the blockchain, when I change telephone or recover a wallet in my computer all addresses n the blockchain Address book will appear in the list of my Address book.
That would only generate a database. Which many of us would not agree due to the gap in privacy and security of this. I am not in favor of anything that can keep a record or address history. Only those who find this useful would agree.
The gap in Privacy? anyway, all history is stored in the blockchain.
The database can be also encrypted with the Public key so only the owner of the wallet with the Private key will be able to decrypt/see it.