It's a good question, to which I wish I knew the answer! Quite clearly there have been times in human history when radical thinking has changed the course of that history. We can see that in retrospect: I doubt they saw it at the time.
After the collapse of the Soviet Union, Samuel Huntington wrote that classic book "The End of History" Great read, and wildly wrong. But I think currently a book entitled "The End of Philosophy" might have a greater longevity. Its arguable that, a little like many aspects of science, where, after the huge advances of the 19th and 20th century, progress, new knowledge, advances in baby steps, and the "know unknowns" become less and less important. It's arguable that the same applies to philosophy: that new thinking is of a diminishing marginal utility.
Just a thought. I tried to study Philosophy via adult education courses three times, and failed abysmally to understand it on each occasion!.
