Design flaw is your assumption, Okie. Apple has determined the cause to be something other than a design flaw:
"Apple has determined that some iPhone 6 Plus devices may exhibit display flickering or Multi-Touch issues after being dropped multiple times on a hard surface and then incurring further stress on the device."
That statement is consistent with the reported numbers of affected iPhones afflicted with "touch disease." That number, after two years of heavy sales, is still effecting far less than an eighth of one percent — and even that is a high estimate — of the iPhone 6 plus phones ever sold, and there are some 275 million iPhone 6 models out there of which around 40% are the plus version.
That 0.125% of 110,000,000 iPhone 6 plus figure represents 140,000 phones, but an analysis of the number of phones involved put the potential actual number at under 70,000 world wide. . . and that is stretching it, especially when the repair depot most involved reported "seeing dozens a month coming in with the problem," and the Apple forum most heavily discussing the issue had just around 700 comments discussing the issue and only about 125 were people who reported then experienced it and the rest merely commenting on those. A design flaw would effect far more iPhones than that.
Again, what do you care, you don't use them?
It is a design flaw. iFixit did a tear down and the circuits are not properly reinforced causing any flexing to break them. No need to argue and get defensive, read the facts.
https://ifixit.org/blog/8309/iphone-6-plus-gray-flicker-touch-death/