“The moment that sealed the future of human-computer interaction for me happened just a few months ago. I was driving my car, carrying a few friends and their children. One child, an 8-year old, pointed to the small LCD screen on the dashboard and asked me whether the settings were controlled by touching the screen. They were not. The settings were controlled by a rotary button nowhere near the screen. It was placed conveniently between the driver and passenger seats. An obvious location in a car built at the tail-end of an era when humans most frequently interacted with technology through physical switches and levers.”
A NUI is still an interface, so how natural can it be.