This might be load of crap, but it's interesting nonetheless.
http://thenextweb.com/apple/2013/06/12/why-does-the-design-of-ios-7-look-so-different/
http://thenextweb.com/apple/2013/06/12/why-does-the-design-of-ios-7-look-so-different/
that article is just verbal diarrhea...