Some Smartasses don't work at 7-11 but carry corporate phones requiring complex pw's. While a (accurate and reliable) sensor controlling purchases would be convenient I'd be happy with it just unlocking my phone.
blackberry's never had any fingerprint sensors, yet still all major corporations used them due to their ability for high security. So your argument really doesn't stand and all you're doing is searching for some excuse that the fingerprint sensor is "the next big thing". All it is is a useless gimmick.