This has less to do with flat design than it does with mismanagement and communication issues. Type flat design in on dribbble and you will be hard pressed to find generic rainbow-barf gradients, and helvetica neue ultra light. iOS 7's default icons were "designed" by Apple's marketing team.This is what happens when you put an industrial designer and marketers in charge of designing an OS.

http://www.macrumors.com/2013/06/12/jony-ive-put-apples-mark...

http://thenextweb.com/apple/2013/06/12/why-does-the-design-o...