The biggest problem is the centralizing of biometric data. That's not only slower but a treasure trove once it is hacked. An Opt-in as you're suggesting would

The biggest problem is the centralizing of biometric data. That's not only slower but a treasure trove once it is hacked. An Opt-in as you're suggesting would be a positive move - even more so would be a decentralized biometric tokenization approach. Device side biometrics that don't leave the user's device.