I can't fathom the number of quirky tricks Microsoft likely has to employ to make Windows work as well as it does... perhaps even going so far as to skip a version number so the world doesn't explode. Speculation aside, there is one odd behaviour we can put to bed -- why do "new" drivers from Microsoft have dates as far back as 2006?
According to the company's Raymond Chen, there is a method to this perceived madness. Long story short, it's to make sure vendor-supplied drivers are always chosen by the operating system above those from Microsoft itself:
When the system looks for a driver to use for a particular piece of hardware, it ranks them according to various criteria. If a driver provides a perfect match to the hardware ID, then it becomes a top candidate. And if more than one driver provides a perfect match, then the one with the most recent timestamp is chosen ... suppose you had a custom driver provided by the manufacturer. When you installed a new build, the driver provided by Windows will have a newer timestamp than the one provided by the manufacturer. Result: When you install a new build, all your manufacturer-provided drivers get replaced by the Windows drivers. Oops.
Rather than come up with some convoluted system to handle this situation, it seems like it was easier to just keep the drivers backdated. Strange, but it's a clean solution to what could have been a messy problem.