After a second though there are more use cases for this:

• enabling audit on existing data (without populating AUD table with fake, incorrect data)
• restoring database from backup that, for any reason, did not contain AUD tables (for example when backed up separately)
• pruning very old entries in AUD tables that are no longer required to be kept by a law (for example: the system may be required to keep logs from last 5 years, so this is not needed to keep 10 years old records)