As with all things security, it depends entirely on your thread model and the value of what you’re trying to protect.

Biometrics can be a much more secure option than using a PIN or password, depending in circumstances.

For example: when I’m working on my laptop on the train or in a coffee shop and I need to log into some website I’d rather use my fingerprint to unlock the passkey than type in a password in a public place where I have no idea who is observing me entering my password.

Same goes for paying with your phone, you can either enter your phone PIN in a crowded supermarket or you unlock with FaceID.

Also, for phones, for a lot of people the alternative to biometrics wouldn’t be a PIN, it would be no authentication whatsoever. Biometrics lowers the barrier to having a form of authentication at all.