More modern look coming this fall.
Jony Ive Put Apple's Marketing Team in Charge of iOS 7 Icon Design
One of the more revealing points in the piece is that Jony Ive, recently put in charge of software as well as hardware design, tapped Apple's marketing and communications team -- MarCom -- to design the look and feel of the icons. Then, with those as a guide, the iOS design teams went to work.
First of all, many of the new icons were primarily designed by members of Apple’s marketing and communications department, not the app design teams. From what we’ve heard, SVP of Design Jony Ive (also now Apple’s head of Human Interaction) brought the print and web marketing design team in to set the look and color palette of the stock app icons. They then handed those off to the app design teams who did their own work on the ‘interiors’, with those palettes as a guide.
The site goes on to note that the design is "firmly a 'work in progress'", and that the look and feel of the icons and other new UI bits are likely to change significantly as the iOS 7 beta proceeds.