Touch ID isn't really biometric authentication. It is hardware token authentication, and that hardware token is unlocked via biometrics. The end application then authenticates with the hardware token. It works similarly to a Yubikey Bio Series token. It is actually an additional layer of protection over what you'd have with most physical hardware tokens, which can be used by anyone who possesses them.

While you can't change your fingerprint, you can change which token is registered with the end application, so that concern is mitigated.