The wright brothers are a good example of iterative invention. They were not the first people to say "You know what would be cool? A flying machine!" That idea was not new. They were the first to make a working prototype. Most of the Wright brothers airplane was just an incremental development on bicycle technology, which was an incremental development on sewing machine technology, which was an incremental development on fire arms technology. They spent about a decade iteratively developing their wings and propellers, alternating between theory, wind tunnel, and working prototypes. With each iteration, they incrementally developed a more practical understanding of bernoulli's principal. The result of all this iteration was the wing and propeller shapes that we know today.
But no one was paying any attention to their decade of iterative work. So when they announced it, the popular conception of a flying machine went from science fiction to reality overnight.
Compare that to today. How many things in your life would have been considered science fiction twenty years ago? Just to name a few: The internet, tablet computers, hybrid cars, drones. I can't see how anyone could say we have stopped making big new inventions. Perhaps we have stopped ignoring the incremental steps that lead to any big new invention.