There are several billion people using many billions of devices every day. From the code in your microwave to massive computing clusters, virtually all of our software can trace its ancestry back to this man's intellectual output. I'm eternally grateful for his life and contributions to humanity.
Consider that every single person reading these words are doing so using technology he created -- after all, even if you're not on a UNIX derivative you're probably on an OS and web browser written in C.
How much code is written every day in C and its descendants? How much more in languages that themselves are written in C?
dmr is part of an very small group of computer scientists that truly changed the paradigm of computing for everyone everywhere (Turing, von Neumann, Engelbart, ...) As long as there are ones and zeros his name will be remembered.