Pickpocketers minimize any physical contact. Biometrics protect against them. PINs do not. Anecdotally I know about an iPhone that got unlocked after a theft at a party. It was protected by a PIN. The owner thinks that the pickpocketer learned the PIN by looking over his shoulder.

On the other side burglars can get into a house and force people to unlock their phones or reveal their passwords, if they care to. There is no protection against that unless those people value their secrets more than the harm the burglars will do to them.

All considered, I unlock with my fingerprints.