Once upon a time it seemed silly to me that people will actually use the screen to type and not physical buttons. To me it is still extremely inconvenient to this day (fat fingers). Nevertheless, the touch screen is so versatile that its versatility trumps this (to me major) inconvenience. In the same way the camera has became a versatile input device. It is used not only for its originally intended purpose (taking pictures), but also to transfer information.

As for the NFC... there are actually wallets that support NFC. Zeus supports it (I haven't tested it but I would guess it works).