the fault here likely does not lie with the aircraft, but more likely with the pilot (and possibly the company culture).
Unfortunately, this is a common problem. I don't know the details of this sad event, but I would not be surprised to read this in the accident report. Demonstrating the company plane, to make it look good for sales, is a role which falls to the company test pilots, as well as doing what they should be doing. It's okay, as long as it's safe. But it's easy to get get carried away.
Seaplanes seem to temp pilots into low altitude maneuvering. I find myself training this out of new seaplane pilots, as they learn a new freedom in flying. Like a helicopter, the unwary pilot can put an airplane into a lot of low altitude places, from which recovery to normal controlled flight could be impossible.