When we first heard the iris scanner rumor about iPhone, I thought it was incredibly stupid. Who wants to hold their phone 6 inches from their face every time they unlock it?
And now Samsung coming out with one explains the rumor. I'd bet Samsung was behind the rumor in the first place to drum up interest in the technology and to legitimize it because "Apple is going to do it, eventually" and make them look like innovators.
Just like the eye-tracking auto-pause video feature, or 3D photos, or docks to turn your phone into a laptop... and on and on.
Gimmicks: because nobody, not designers, not consumers, not even science fiction writers, are dreaming of personal computing technology beyond that which we already have.