Apple made the filing in the same year as the first iPhone was released. I can't be the only one who has wondered before why Apple haven't made an iOs gamepad - or released a reference design for the 3rd party peripheral manufacturers.
The answer probably is that Apple have been able to sell plenty of iPhones without such a gamepad.
Apple historically have been a little wary of the games market too - in the Mac days they feared that games would negatively affect how people saw their computers.
The Android hardware market is a bit more fragmented ( witness the inability of Android phone vendors to settle on a standard for wired remote control headsets, or music/charge docks) and no big player (Google?) took a lead on gamepads.
Sony made a decision not to release a proper 'Playstation Phone', probably because it would cannibalise sales of their dedicated PSP machines. Sony then tried the 'Playstation Mobile' initiative - but only a small number of phones (even fewer non-Sony phones) were supported - so it probably didn't gain enough critical mass of users and developers to continue. They seem to have a change of heart (part of the 'One Sony' strategy), and have made their recent phones and tablets work with Dualshock 3 controllers 'out of the box' - and other vendors' phones can be made to work with them too.
Ever more Android phones now support USB OTG, which is a straightforward if inelegant way of adding a gamepad to a phone. Not all games support gamepads, but the classic console emulators for Android mostly do.