Of course, a new generation that hasn't used a real camera with a mechanical shutter that clicks or hasn't read a lot of printed books might find skeuomorphic design unappealing. (Oddly, skeuomorphic design has been pushed to the extremes with the photo sharing app Instagram, which gives digital photos an "old" look and enjoys popularity among the younger generation.)

Given Apple's global audience, Yamaguma believes Apple should embrace a broad range of design concepts, including the use of skeuomorphic design where it makes sense-at least for now.

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"Design is dynamic and not a straight line," he says, which is why Apple designers shouldn't take sides when it comes to concepts such as skeuomorphic design. But he admits that certain concepts might outlive their usefulness.

"In time, those [skeuomorphic] metaphors will become less and less important," Yamaguma says. "There may be a time when they do become obsolete."