Toyota profits when their corporate image improves; it is clearly the case and we have recent developments to prove it. They are still recovering from a loss of confidence and they did lose sales because of it.
This is not a matter of Toyota trying to build in obsolescence, they are not the only car company in the world. If they were, then there would be a profit motive to do so, but they are not in that position, and never will be.
This is more about Toyota vs Volkswagen, not to mention other competition, some of whom are yet to emerge from China and India, and there is a net benefit to building more reliable motors and by extension, more reliable vehicles overall.
With the reality that consumers are now financing over as much as 84 months, this aspect of choosing a marque becomes ever more significant in buyer's minds. Toyota as well as every other automaker must compete on long-term reliability even more so than in the past, with the "old school" replacement period of three years.
A healthy skepticism is definitely worth consideration with any corporate move, but it is also worthwhile to consider that sometimes a company and the general public have aligned benefits. Perhaps more significant is the simple realization that no company the size of Toyota acts with a single mind; there are groups within the organization that have conflicting goals and motives.
What that means is even if it is true that they would use any information gleaned to seek short term profit versus the long, it is not certain that the move by those who would advocate it would prevail over those who would use it to improve the product's life span.
At a minimum, this may be an illustrative example where engineers within Toyota really do want the answers that study of this particular vehicle may offer enlightenment. Exactly what results when all is considered by management is yet to be determined, and the possibility that there is a benefit, eventually, to consumers is just as likely as the opposite.
It cannot be dismissed that maybe Toyota's marketing department would like to exploit the mileage milestone as well. After all, this is an engine Toyota has already built, not one somehow transported from the future, and therefore is relevant to current sales.
Publicly traded corporations do have a fiduciary duty to shareholders, but it also must be said that Japanese business philosophy puts a higher value on long term sustainable benefits over the North American practice of next quarter's results over those of five years from today. It's a different culture, and well established by history.
In the end, I don't see this as a sinister plot to rob us of our vehicle reliability. Quite the opposite.