While I agree that for many people this isn't really a threat, for people in urban areas I would be more wary. Phone theft is already a huge deal in cities like NYC, just ask the police there. There is a large black market for stolen phones, particularly new iPhones. If a ring of phone thieves can set up a shop for $1000 to get into the phones with touch sensors on, even if they don't get into all of them, it's something to be concerned about. Basically, with a little time, some luck and some equipment, they can circumvent Activation Lock, the biggest real security feature of the new iPhone.
So how long until Apple has to issue free lint-free wipes to clean your phone of fingerprints like they did with the iPhone 4 bumpers. 😉