I remember many strikingly similar designs as these "new" concepts of Windows 8 tablets being presented 10-15 years ago as new concepts of computing devices powered by Windows CE Handheld PC Edition (with some of them being actually manufactured then).
While I agree with your general point, it is worth remembering that in the last 10 - 15 years battery life, processing power (in small devices) and the capacitative touch screen have improved dramatically.
It's a little bit like comparing the first truly practical cars (Model T vintage) to the very first cars and saying that they haven't done anything revolutionary.
