>why spend time implementing what isn't needed commercially,
Because more often than not they go to extreme lengths to block something, inventing complex security solutions to stop you doing something reasonable that you would buy the device for.
Like Nintendo stopping me running Mplayer on the new Wii - when I would buy a second one if I could.
Apple blocking you using the iPhone as a 3G dongle is for the benefit of the carriers.
But if Android (or Apple) let me use a USB dongle there are a bunch of apps we currently run on Windows CE machines that I would switch to smart phones.