You can always lose your password, most people don't lose their thumb or eyes.
Actually some people do lose their thumb or eyes. One can just write the password on the outside of the phone in order to not lose it. This is the essence of the CCC hack over a year ago.
http://www.ccc.de/en/updates/2013/ccc-breaks-apple-touchid. Yes Apple is that reckless when it comes to the security of their customer's information.
Um... Ok. Then show me statistics of how many people in the world lose both their eyes and thumbs, I'm assuming not much? If it's not much, I think you're proving a good point for this type of security. Someone had to recreate someone's thumb! That's a hell of a lot harder to do than stealing someone's credit card or being apart of other illegal schemes.