For example, Android devices work just dandy with Bluetooth mice. And keyboards. And USB mice and keyboards. Have for years. Some, like my Asus Transformer here, offer decent clip-on keyboards, for those who prefer them. I can plug in a full sized SD card from a camera or camcorder, plug a USB stick or HDD in, and backup my media.. one of my main reasons for dragging a laptop everywhere in the past. I can also develop Android apps on Android.. try that on iOS or Windows RT.

That's kind of a fundamental.. Android has always seemed designed to enable a stand-alone device for general purpose computing. IOS devices were originally PC accessories, and while they have slowly evolved, the cord doesn't seem cut. Similarly, a Windows RT device seems only something you'd want as an extension of your Windows desktop. Like iOS, there seem to be artificial blocks set up to prevent these from being full fledged personal computers.