They are also much more heavy duty u-joints vs what we have on our bikes I would assume.. plus some of those have zerks to keep them lubed.. not available to us..Every tuck out there has U joints exposed to the environment and failures are rare. I would think it might have to do with drive shaft angles. If your building a car a incorrect drive shaft angle can cause all kinds of problems. I really BMW would identify the fault.
GS bikes appear to be the heavy hitter here as those bikes are more likely to cross rivers and also deal w/extreme angles going over tough terrain..
It doesn't really concern me much... I'll keep checking the DS and the replacement is very easy vs a u-joint on an ST so that's a good thing.
BMW identifying the fault... HAAAA!... this should be in the laughing section... admitting wrong will never happen.