The reason? Golfers (whether they're amateur, recreational, or pro) who have poor balance make have less consistent contact in the 'sweet spot'. When the insoles were introduced, they were seen to make a positive difference on the golfers ability. This inconsistency was assumed to be due to the fatigue associated with a full day on the course. The introduction of the fatigue reducing insoles helped keep muscle strength and balance up, therefore helping make a positive influence on the golfers game.
So there you have it. Next time you hit the course, and your golf buddies ask "How did you get so good?" you can call out Wiivv as your secret weapon!