Anyone using a "slide to unlock" feature on their iPhone or iPad should thank Apple's Greg Christie, who is leaving the company.
Now that Christie, who was a vice president of human interface, is gone it seems that more power is concentrated in the hands of Jonathan Ive. Apple's senior vice president of design, according to the Guardian. Other reports have also said that Christie and Ive didn't agree with the design direction of iOS 7 which caused friction between them. From 9to5Mac:
When Ive tasked Apple’s Human Interface team with redesigning iOS 7 to include an entirely new look, Christie and Ive reportedly clashed over design direction, after which Ive is said to have circumvented Christie’s leadership of the team during the new operating system’s development.
The iOS 7's radical design was the first time Ive controlled much of the software design -- because former iOS chief Scott Forstall was fired by Apple's chief executive Tim Cook. Sources inside Apple say that Christie wasn't ousted, but other sources seem to indicate Christie and Ive's relationship was a difficult one and the cause for his early retirement.