The perfect use case for biometrics is identifying people who don't want to be identified specifically because they can't change their "password". For example, prisoners, fugitives, enemy combatants, people trying to use software they are not licensed to use or listen to music they have not properly licensed.
In the future the bottom 64 bits of your ipv6 address will be a unique biometric identifier that all licensed internet devices must collect and send with each and every packet.