Star Trek speaks to some basic human needs: that there is a tomorrow — it's not all going to be over with a big flash and a bomb; that the human race is improving; that we have things to be proud of as humans. No, ancient astronauts did not build the pyramids — human beings built them, because they're clever and they work hard. And Star Trek is about those things.
Interview (20 September 1988), included in Star Trek: The Next Generation Season 5, DVD 7, "Mission Logs: Year Five", "A Tribute to Gene Roddenberry", 0:26:09)