[1] : http://matt.might.net/articles/phd-school-in-pictures/
Also, I think Google came out of Page's & Brin's PhD work, but they decided that building a company around it was a better idea than getting PhDs for it.
This is a nit pick, but all the examples you gave are of people who actually changed the world, not just some sliver of academia.
That said, changing your sliver of academia is likely to imply changing the world if you're in certain areas of math or science or engineering.
The only time when you can change your sliver of academia but not change the real world, is when your sliver of academia does not contribute to the real world, which is (unfortunately) common, particularly in the humanities. (Which is sad, because we actually really need good humanities study/education in order to build a good world.)
I think that's going way too far in the other direction.
I certainly know of PhD theses in my research area that have made contributions to the area, and these contributions (or derivative ones) are very likely to make it into real products eventually.
A lot of PhD computer science students have the benefit of taking 5 years or so to really work hard on something consistently that would be very hard to accomplish with the same level of rigour in industry.