Ask 10 people on the street, whom have never seen IOS7 or an iPhone, which icons were designed in 2006 and which icons were designed in 2013, and I suspect most people would associate the OS7 icons with 2006.
I know many on this forum are relatively young, but the new icons are very similar to the icon designs that we began to see in 1996 after the release of Windows 95. That's when we first got icons with 256 colors; the OS only shipped with 16-color icons, but users could add support for 256-color icons with an add-on (Microsoft Plus!). Over the course of the next five years, third-parties released flat 256-color icons in all shapes and sizes.
OSX's claim to fame, when it was released, was its design with 32-bit color icons (24-bit color plus an 8-bit alpha channel). OSX was the first consumer OS with detailed, three-dimensional icons with semitransparent areas like shadows, anti-aliasing, and glass-like shapes. Apple's three-dimensional icons have been the envy of Windows users ever since. Windows users languished for years with flat icons lacking depth, because the platform lacked support for the alpha channel necessary to deliver icons with transparency and shadows.
