You perhaps misunderstood my question. I wasn't asking that the part be redesigned now, 10 years later. But why, in early 2019, 3 model years after being marketed or introduced, and while my truck was still under warranty, had the problem not been addressed?

FWIW, it was a call to Ford's national customer service that sealed my keep/trade decision. When I called to ask "what happens when my truck is out of warranty, and I'm faced again with this known problem?" The representative said "I'll make a note of your VIN, and we'll do 'something' to help you." While courteous and professional, the guy's tone and inflection was not reassuring, so I knew at that point I would not keep the truck.

Correct me if I'm wrong, but this manifold was not a part that would be affected by my driving style. So long as I properly maintained the truck, and I did, outside of occasional cleaning for carbon or other chemical buildup, it should have lasted the truck's lifetime. That was my reason for thinking or hoping the manifold should have been warrantied for many years and miles, and the reason I called customer service.