Though it seems like a simple game mechanic (and it is), the dodge skill is one of the most important components of running a 'cinematic' style adventure game. It is one of the things that really sets the D6 system apart from games like D&D, where how much armor/magic-protection you had was the primary determinant of whether or not you got hit in combat. Though armor is still useful in the D6 system, the dodge mechanic allows you to play the kind of heroes you see in movies—who usually don't wear much more than normal clothing. Since this is what we see most of the time in the Star Wars movies, its nice to see that the game supports this (and as a side note, this is yet another reason I don't think the D20 system captures the 'feel' of the movies as well).
The skill was defined in the last generation of rule books as: "a reaction skill used to avoid any ranged attack...Character's using this are doing whatever they can to dodge the attack—slipping around a corner for cover, diving behind cargo containers, dropping to the ground or any other maneuvers to avoid getting hit."
Pretty self-explanatory, but also I can see where some people might not consider it terribly realistic. Well.. it isn't. But then, Star Wars isn't a terribly 'realistic' setting. Its cinematic. Heroes do things that, in 'real life', would probably get them killed. Thus, in my own mind, the Dodge skill has had to expand a bit beyond its basic definition. It isn't as simple as a character just being able to see an incoming attack and move out of the way.
First of all, to me dodge includes an element of 'luck'—a commodity that heroes (and major villains) seem to have. And to me, this is even 'demonstrated' in the movies—when you look at just how bad a shot the Imperial Stormtroopers seem to be. Since these guys are vaunted to be 'accurate' shots, I can't think of many other plausible reasons for them not hitting.
But, in talking with my friend Philip, I have come to see the dodge skill as an overall kind of 'awareness' that people get through training and combat experience. It is the ability to know how to subconsciously take advantage of cover while moving. To know how to 'fire and move' in an unpredictable manner. To me, this makes a lot more sense than imagining a person who can see incoming blaster bolts and sidestep them.
Indeed, when I first began to play the D6 Star Wars system I rather quickly had to make some house-rules regarding its use. Most notable of these was the rule that you can't 'Dodge Forward'. Often, my players would have their characters move directly into the teeth of enemy fire, dodging as they came to close the distance. To me, this pushes the bounds of even cinematic realism. I mean, it was like they were becoming 'ninja masters', sidestepping blasts. Now, in order to close the distance, you have to move obliquely to those who are shooting at you (thus making approaching enemy fire a lot slower).
Anyway, those are just my random thoughts on the subject—and like a lot of D6 things, it 'feels right' to me, and has worked for quite a few years now.