Star Wars has the 3 original films, which a lot of people have seen
but Star Trek is on TV ALL THE TIME (in the UK at least). The original, TNG, Voyager, Deep Space 9, there's so many episodes of them and you can catch repeats every single week (as well as the new Enterprise episodes)

I mean, that's something, that there's so many shows running for so long

I wonder if Star Wars did a series, if it could sustain as well
but as it stands its kind of an unfair comparison - three blockbusters vs. numerous tv episodes