you are correct. the only info stored in my phone are MP3s and a few photos of my pets. and even those are backed up to other media. that is because it's a smartphone. it could be easily lost, stolen, broken, smashed, crushed, disassembled at any time. a fingerprint scanner is just another redundant piece of hardware that can fail or glitch out and lock a legitimate user from their device.
it's just like those newer cars with VATS security. i have one of them, a Pontiac Bonneville with a chip inside the key, supposedly the only key that will start the car. unfortunately for GM, they realized later on that the system failed often and prevented the owner from using their own vehicle; in essence, preventing the person from stealing their own car. radios with TheftLock also had issues and that one remains unresolved overall. i am not sure about you guys, but i am not very keen on paying someone $150 to unlock my phone if such a system fails. it's just VATS systems for our phones. I feel that anyone keeping extremely sensitive data on a device likely to be stolen or broken, needs to seek mental help. if you have bank info or such, it's far safer to be stored in a fire-proof safe somewhere. such a safe would benefit far more from fingerprint/retina/biometrics if you ask me.
Samsung Galaxy S3 (Stock, rooted TouchWiz)
Samsung Galaxy Tab 3 7.0 (non-rooted, stock)
Samsung Galaxy Tab 2 10.1 (obsolete, slow, rooted)
Samsung Galaxy Note 10.1 2014 Edition