For me, the original SW trilogy works better than either the prequels or most of the EU because of the plot holes, lack of explanations and so on. Why? Well, thing is, fundamentally, the entire concept of SW is stupid. Really stupid. And trying to explain it, to make it coherent simply can't work because of the inherent stupidity. And so the original films didn't really even try. If anything, they ran off of the Rule of Cool: The Force? Space magic, which is cool. Lightsabres? Frikkin' laser swords, how awesome is that? Spaceships working like WW2 fighters IN SPACE? So much fun to watch. Evil dudes with evil space magic? Cool. Incest? Hell yeah. And so on. By not even trying to justify these things, it allowed them to be great entertainment and escapism. It's not a deep meaningful complex story, but it's not meant to be, it's a modern fairy tale. And at that it works brilliantly. I wouldn't even say it's a matter of letting the viewer make his own explanations, instead to me it's more about explanations simply not being relevant to the story being told.
The prequels (and much of the EU) on the other hand, tried to add some level of explanations, justifications and mechanics for these things. And yet, all they manage by doing this is to highlight just how ridiculous the underlying mechanics of Star Wars are.