Besides overusing a certain vowel, there is something in common between the Wii and the iPad which one seldomly sees mentioned: They are both all about an input device.
This is very obvious with the Wii. Nintendo’s advertising didn’t show anything else but the nunchuks.
It is somewhat less obvious to the iPad, because the touchscreen is transparent and mounted atop a display. The eyes get caught in the pictures o we forget the sensor. Nothing about this device matters except the touchscreen. Everything else is there to make the touchscreen work it’s “magic”.
Part of the reason that Apple had to create the iPad is that the touchscreen seems to validate the old (and heavily criticized) idea of «direct manipulation». A “computer for the rest of us” has always been just stupid since the rest has no interest whatsoever in computations, so Apple wanted to make computers be not about numbers and Maths, but about stuff. That is why touching the things inside the computers sounds like it should be important.
Also, Apple had to pretend to have something called a «killer product» and input devices do not sound sexy, so they find different ways to say it. But of course it is a fragile proposition, since basically input devices are not sophisticated — they can be but the difference is never really noticeable. That is why the Kinectic could come along and eat Nintendo’s cake.
In fact, the thing about input devices is that the complexity of the computer gives us interesting results from simple methods. A mouse is not an engineering feat. It generates a continuous stream of useless coordinates, but the computer filters them into useful clicks. The mouse matters because we can use the computer to discard almost the entire information content coming from it.
Of course humans care about things that have nothing to do with computations most of the time, so the coarse hacks that we call input devices can feel better than a more precise instrument like a keyboard (or punched cards, for that matter). Input devices tap our basic sensibilities. That’s why they are important. That is why the Wii had a stronger influence on gaming than the other consoles of the same generation.