I was actually a Trekker before I was a Wars fan, so I love both equally. I have a good friend who loves Star Wars, but hates Star Trek. I keep telling him I'm going to convert him, but he says it'll never happen.
The real reasons are simple, as I have talked with many fellow geeks about it. First, Star Trek is too cerebral for most casual viewers. Star Wars is pretty much non-stop action. Also, SW is more of a fairy tale setting, just with lasers and lightsabers. Lucas took (stole) the best from Kurasawa, Flash Gordon, Arthurian legend, Greek mythology, world religions, and modern political strife and made a universe of space wizards and pirates.
Both franchises look at societal issues, but SW does it in broad strokes. Trek always looked at singular issues - racism, war, injustice, etc. - and set them in a sci-fi setting to make people look at it without realizing they were looking at a real world issue.
Also, SW is made to appeal to a broader audience, whereas Trek appeals more to an intellectual audience. If that makes sense.
So, Live Long and Prosper, and May the Force be with you.
