The cause of the failure is not upgrading the gears, it is driving the car with upgraded gears at twice the speed limit.
You can't just slap on an aftermarket performance part (in this case gears) and push the car's limits without accepting that you might require other prerequisite upgrades
And my stated "5% of owners" is probably a gross exaggeration
Better engineered driveshafts are available. If you think Ford / Ford Racing should offer an aftermarket driveshaft, or even as a factory option, that makes perfect sense, but to put in a performance driveshaft as a stock part and bump the price of the V6 is a bad business move.
Yeah you're right what's a few humans lives if it keeps the V6 price down a few hundred bucks.This isn't a saftey concern at all.