Too close to the edge?
The comments have engaged my relatively primitive metalurgical skills. I would like to point out that a frame's ability to survive a race, or a dozen races, is no indicator of how it will handle the stresses of 20 or 30 thousand miles. Aluminum is very light for its strength, but it is a brittle metal that is prone to stress cracking when subject to vibration over long time periods. Steel, on the other hand, is not prone to that kind of failure since it is more ductile. Aluminum frames can't be designed to handle the kind of flex that can be engineered into a steel frame, at least to my knowledge.
I know that reputable sources who are familiar with Ducati frames have said that the male slider fork assemblies that the boys at Ducati are so fond of have less flex. Therefore the frame needs more. I also know that Ducati's engineers design the amount of flex in the frame.
Steel trellis frames are essentially built by hand and are expensive. Aluminum frames are cheaper and retain the same lightness and strength of trellis frames. A steel frame can't be as strong and light as an aluminum frame without going to a trellis type construction. Which is more bucks.
Are we reaching the point that the aluminum frames have pushed the envelope too far? We won't know unless people start riding these bikes for thousands of miles. It does worry me that mighty Honda has had problems with the (aluminum) frames on the Gold Wings.
Engineering is an art that, by its nature, pushes the edge. The old joke about bridge design is "keep making it lighter until it falls down, then back off a notch." During the 50s there was an over engineered airliner which had the minor problem of losing a wing at a certain point in its life due to vibration cracking. It took a while to figure out the problem since it was hard to do an extensive analysis on metal that had failed, then fallen 20,000 feet, before it could be examined.
I know there's a lot of knowledge out there in the MOron community. I could be full of it, but I certainly wouldn't want to plan doing much touring on a bike whose frame was designed without consideration for vibrational stresses. You simply can't escape vibration on a motorcycle with an internal combustion engine.
Maybe these failures are only insufficient engineering. Maybe they are due to some special stress the bike received before its sale. Or maybe the engineers are chasing "light" a little too hard.
Francis