Why is 5th wheel standard vs Gooseneck?

I have a trailer Saver now (TS3). If I were to make a change I would consider the Goose Box as it has some real design advantages. The attachment point to the truck is low reducing the hitch angle which reduces the amount of chucking forces relative to bouncing forces created by the trailer. Consider the Goose Box image; the forward high hinge point relative to the ball will allow the hitch to retract some when compressed thus mitigating some chucking forces. Solid engineering was used when designing the box.

Any type of soft joint hitch/pin box has to be easier on the trailer frame than a solid hitch and solid pin box.