I have a friend who works at Wacom and I asked the same question. He mentions that Wacom doesn't allow Microsoft to add the "OneNote" button because this will affect their sales of their product. So it seems like this is more of a political issue than a technical issue.
Wacom does not use a battery stylus. It depends 100% in the pen being by the screen in order to register the input at all. MS had this idea to wake up the tablet with the pen being away from the screen. You cant do that without a battery. Hince, you cant do that with a Wacom tablet. MS got this stupid gimic idea that turning on the tablet by clicking a pin will sell $1000 tablets. Its cute, but it wont sell a single one more then if it didnt.