Scott Forstall was fired for the Apple Maps mess up. He championed good designs like this. When he left it was a race to the bottom at Apple for their UI/UX.
Scott created a lot of friction and animosity amongst various high-level managers and executives. Steve protected Scott. With Steve gone, the other executives had to deal with this issue. I won't name who, as I am sure the story has been told elsewhere, basically said Scott had to go or they would go. Scott may have gotten Apple Maps pinned to him on the way out the door, but there were many, many more issues leading to his departure.
