when they turned the 3.5L sideways there wasn’t enough room for the water pump externally in smaller vehicles like the edge without major super expensive modifications to multiple vehicles. They didn’t just forget that it could be a problem. At the time, water pump failures were pretty rare. In hindsight it looks like a terrible decision but like most things it made sense at the time.
As for the PTU fluid - it is lifetime provided it doesn’t get overheated. Once it gets overheated it starts to fail. It appears they didn’t anticipate whatever causes the overheating. It is fair to blame them for not making corrections fast enough. However, simply adding a fluid change recommendation of 50k miles wouldn’t necessarily help. If the fluid overheats at 51K it will probably fail before 100K. The fluid doesn’t wear out unless it overheats.
What they should have done is extend the warranty on both the PTUs and water pump to 100K miles. But of course that costs money so it becomes a business decision.