What are people going to do when, in the all-too-near future, criminals begin sharing and selling databases of stolen high resolution finger prints?
One theft isn't practical? How about a million? Driven by a never-ending pursuit of monetary gain via crime; with criminals always happy to conquer the latest technology wave. There's absolutely no reason to think that criminals won't amass substantial finger print records just like they do any other intimate information they can get their hands on, from SS numbers to passwords. It's not a question of if, but when this starts becoming common.
All it requires is linking finger prints to something valuable at a mass market scale, and that will drive an unlimited criminal demand for finger prints.
It's not about the iPhone. It's about a consumer shift to finger prints as a primary security feature, and whether that is sane (with the iPhone potentially setting the trend given its cultural status).