If It's Good for a Mouse, It's Bad for Your Fingers
Even if we ignore the hardware problem, the fundamental design of Windows and its applications is completely flawed on a touch-based device. Yes, you can mimic clicking with a mouse on a multi-touch display, but a good interface for a pointer is not a good interface for your fingers. Back in the 50s, a psychologist named Paul Fitts devised a model of human interaction with machines that is still very relevant today. People call it Fitts' Law, and it's a mathematical formula that describes the time it takes to interact with something as a function of distance moved to a target, speed, and width of the target along the axis of motion. Applied to a mouse interface, it essentially says that the time it takes to complete an action is a function of the distance the mouse has to travel, the speed it moves, and the size of the target (icon, button, menu, whatever). In other words, the further the mouse has to go, and the faster you move it, and the smaller the target you're trying to click on or drag to, the worse your accuracy is and the longer it'll take you to do that action.
A good mouse interface is therefore one where interface elements that are used together are near each other, and where targets are reasonably large but not so big that they take up too much space from the actual content of the application. Also, the edges of the screen are golden: you can't accidentally "over-shoot" your target because the mouse stops moving at the edge of the screen. This is why the taskbar in Windows and the dock in OSX are so successful - you can easily and accurately move the mouse pointer down to the bottom edge where your target is pretty wide and the edge of the screen keeps you from going too far.
Now, consider what makes a good interface on a touch-based device like a tablet or smartphone. You have no cursor starting position as you do with a mouse, so it doesn't matter if interface elements are close together. You're just as accurate at tapping on an interface element anywhere on the screen. In fact, putting interface elements too close together is actually detrimental to your accuracy, because our fingers are a bit imprecise and it's easy to miss your target by a small amount. Good touch interfaces space objects apart. On a touch device, you want to avoid the edges of the screen because users can, and do, tap outside the display area, which will register no action at all. Then there are those interface elements that are simply vestigial wastes of space on a touch interface but necessary in a good mouse-driven design, like scroll bars.
In other words, the fundamental principles that make a good mouse interface are antithetical to what makes a good touch interface. And I haven't even gone into multi-touch gestures like pinching, multi-finger swipes, and other features that a single mouse pointer can't replicate!
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