Your wallet is protected by the other person not having a knife. Your cell phone's data is protected by the other person not being willing to use their knife to cut off one of your fingers. ;-)
http://www.engadget.com/2013/09/16/why-a-disembodied-finger-...
By the time you defeat TouchID, the device will be useless anyway. It's more than secure enough.
http://arstechnica.com/apple/2013/09/chaos-computer-club-hac...