The Death Star
In Return of the Jedi, the Death Star proves that bigger isn't always better. It's a giant, technologically advanced weapon that symbolizes two unsavory aspects of the Empire's flawed worldview.
First, it's the size of a planet. Know what else is the size of a planet? The Emperor's overblown ego. He has Darth Vader to do his bidding, he thinks corrupting Luke will be a cinch, and he doesn't even entertain the thought that the Rebels might pose a real threat. In the end, the Emperor's Death Star-sized arrogance not only leads to his demise, but also gets the Death Star itself blown up. Blown up real good.
Second, the Death Star symbolizes the Empire's overreliance on technology. For these guys, there's nothing that a machine can't fix—or really, nothing that a machine can't terrorize and force to submit to the Empire's shady will. If Darth Vader is, as Obi-Wan tells Luke, "more machine than man," then the Death Star proves that the same is true of the entire Empire, floating in space in their big, shiny ball of hate. Until Darth Vader is unmasked, there isn't a shred of humanity on board.
In contrast, the Rebels occupy Endor, a.k.a. nature-palooza. With the help of the Ewoks and their primitive weapons and tactics, the Rebels take down the Death Star's defense shield and then the Death Star itself. Ultimately, the destruction of the fancy-pants Death Star is made possible by a bunch of aboriginal teddy bears with sticks and rocks, symbolizing the superiority of the natural world over technology.
As Luke's lightsaber, Leia's gun, and the existence of C-3PO and R2-D2 demonstrate, it's not that the Jedi and the Rebels don't believe in using technology; they just don't lump all of their faith into it. Instead, they put their faith in their friends and the land first, and save tech for Plan B.