Look at Jony's designs, everything from the first iMac to the soon to be released Mac Pro can be boiled down to a rectangle with rounded corners. 20 years of the same core element has caused it to become stale.
You can’t blame Apple as it’s one of the few company that actually tried alternatives... that market rejected.
To name a few : the twentieth anniversary Mac, the "Luxo" iMac, and more recently the trashcan MacPro