None of us know exactly why some Camrys eat up their lock-up clutch and others don't. Seems though that it must have to do with certain driving patterns causing the TC clutch to get worked more, perhaps by passing through certain speed ranges more often, where the clutch slips almost continuously (but which I would hesitate to call "abuse", other than the owner's and Toyota's failure to identify such driving patterns as "severe service" and thus calling for more-frequent fluid replacement).
Somehow, Toyota's pre-launch product testing failed to simulate such driving patterns that would cause the premature failure of the TC friction surfaces. Either that or perhaps some change occurred during the change from prototype manufacturing to production manufacturing, although this seems less likely since a major transmission manufacturer would tend to prevent significant differences like that from occurring.
The fact that this problem persisted as long as it did tells me that Toyota/Aisin was kind of ok with allowing that a certain rate of failure among the hardest-worked TC's was acceptable, at least to the point of not taking swifter actions to stop this problem. Surely some of these TC clutches were going out within the first two years, but which didn't raise much alarm until problems at the "public product image" level arose.
So I am not really surprised that a certain number of the upgraded TC's are now going out, but again which aren't occurring at a high enough rate to cause Toyota/Aisin much concern at this point in time when all car makers are perhaps more focused on their rolling out the next generation of hybrid and electric cars that will dominate the future.
I would recommend that owners of these cars take a harder look at how their (and their car's previous owner's) driving patterns might well be into the range of what Toyota call "severe service", and where more-frequent fluid replacement should be done, perhaps well before even the 60k prescribed interval. For my used-car purchase, I replaced the fluid in my 2015 Camry LE at around 24k simply to flush out the break-in fill, which hopefully kicks any TC clutch problem much further into the future.
