Garland,
You may be right. It does seem that the perimeter weighted irons and big heads allow average golfers to get more shots airborn, but it would take the invention of the magnetic golf ball in combo with steel cups to really lower scores, so its hard to quantify.
So, if new clubs and balls are selling more hope than change, that leaves the question of what are the best golf related inventions in the last 40 years?
It might be some of the maintenance equipment that makes the supers job easier, less toxic golf course chemicals, tee time booking services, more water efficient irrigation systems (really a slow evolution rather than one time invention in most cases listed)
What else? Cart girls? (insert smiley)