Significant route info would be almost mind numbingly tedious for most pax. Perhaps an announcement at the beginning of a flight: "Our flight today takes us over... then we turn east over... we'll pass about four miles south of central..." etc. On the fly commentary would be more than the pax - and the flight crew - could deal with.
And you can use GPS receivers onboard but not all airlines and always at the discretion of the crew. Do a forum search and you'll find plenty of discussion about it.