Scott Forstal was forced to leave Apple after the iOS6’s new Maps application problems (great interface and 3D vector rendering – lighter than Google’s -, however data weren’t all reliable). He originated the iOS era (from Core Animation to WebKit’s CSS effects, and more recently Siri and Maps) however there wasn’t much innovating recently in UI design (notably iOS features added to OSX – like the launchBar – didn’t brought real value).
Since Micosoft’s new system (merging desktop and mobile, and inspired from Apple’s old Hypercard from 1988, and OpenDoc from mid-90s), Apple had to rethink its UI design strategy. Moreover there was strong competition with other lead members.
Then Jonathan Ive will take leadership and direction for Human Interface besides his role as leader of Industrial Design. Eddy Cue will manage Siri and Maps (also iTunes Store, the App Store and iCloud). Craig Federighi will manage both iOS and OSX, and Bob Mansfield will lead the wireless team.