Track miles take a tad longer to accumulate than Interstate parade miles. Just say'n.
And it's not just BMW that do odd things...just because. Take Suzuki's oil filters, I can walk into any NAPA, Autozone, or even Walmart and get an oil filter for a Kawasaki, Yamaha or Honda. But Suzuki has to use their own special thread size on their filters. Meh.
Then again it could be part of the brand loyalty program...if you bought all the tools you need to work on a BMW how many latte's worth of new tools would all these high mileage Bavarian DIY'ers have to buy if they went Nippon?
Oh and as a frame of reference, I ride a ZX-6 with 180k'ish on it. 150k I have put on in the last six years, and the only time it has left me stranded by the side of the road is when it snapped a throttle cable I knew I should have replaced.
Then again, I've ridden with guys that put monster miles on their sportbikes, but change them like their underwear (bonus points goes to the retired steelworker that had a Bandit when I met him, and over six seasons has gone through a dozen bikes).