perhaps you'll enlighten us.
I can see only two reasons in my view is a) obtain a protection for their IP b) draw a line in the sand to say we thought of this on such and such day.
My point is this sort of UI element should not be patentable. It will stop others on improving and taking it further. The end result of IP protection is less innovation. It's not like they've sweated over this design for years and spent gazillions of dollars.
If it was any other company I'd be almost happy to believe that they'd open source the patent for free, but with Apple ...