As long as we're sharing anecdotal evidence about the success and spread of d6 Star Wars:
d6 Star Wars was my first RPG, it's what got me into gaming. I discovered it through references to it's source material in other Star Wars books, and started playing it because it wasn't D&D (my father having banned me from the game because he heard it was satanic). I started a d6 Star Wars campaign which at it's peak had 8 PC's, and just about everybody in the gaming club was in for at least a little while. Among all the gamers I knew, it easily was the #3 game in all of gaming, behind D&D and Vampire (and was giving Vampire a run for it's money sometimes) and just ahead of DeadLands and GURPS. People I knew who literally hated RPG's created a character and played a session or two, it was somehow an incredible crossover product outside the normal gaming world.
My great campaign lasted about a year, ending shortly before Episode I came out (and played through the collapse of WEG and the loss of the license). From that point on, we played a series of one-shots, until finally the d20 game came out, and everyone I knew migrated over to it. We had piles of stuff we hand-converted (using the conversion rules in the back), and saw gaps, but we also liked the d20 rules and saw potential in this new game.
Even now, as the RPG is dormant (I won't say dead, it's weak but still loosely supported), it's still popular. I run across gaming groups who are playing it, people who talk about stats, and the newest web site update with new stats comes up in random gaming conversation always within a few days of it's posting.
Star Wars is the biggest license in gaming, and when it's fully supported a Star Wars RPG can easily be the #2 or #3 game in the entire industry. d6 or d20.