Earlier quoted context omitted.
There's a lot of stuff that depends on the secure element - in fact the phone would be quite useless without it. In fact, when you first reboot your phone, even contacts cannot be accessed until you authenticate with your passcode to unlock the secure element. Incoming text messages only show the phone number. You're right, however - a Touch ID sensor that cannot be verified should not brick the phone. Apple should j…
The issue is Apple cannot verify a secure touch ID replacement over a compromised touch ID replacement. Without knowing if your replacement is secure the change potentially compromises the security of the whole device. IMO bricking on touch ID issues is extreme, but maximises the security of the device.
The phone would still work perfectly fine and safe if Touch ID would be disabled and input from the sensor wouldn't be trusted.