If you want something done properly, as the old adage goes, you have to do it yourself.
For the longest time, the failure to produce a good, usable Windows tablet was twofold. Microsoft lacked an operating system usable with finger input, and the PC OEMs failed to produce devices that were thin enough and light enough to be comfortable when handheld.
The first problem is, to a greater or lesser extent, addressed by Windows 8 and its ARM counterpart, Windows RT. But the software is nothing without the hardware to run it on.