Towards the end of Revenge of the Sith, there is a scene in the Senate where Palpatine announces that Jedi have turned against the Republic, he has basically executed them all, and is going to disintegrate the Republic to form a Galactic Empire, which he would rule. Now, doesn't it seem somewhat odd that the Senators of the Republic would accept this without any objection and with thunderous applause? The senators represented democracy, and must have had some sort of power in the Republic, so why did they just accept dictatorship, and basically being stripped of all their powers? At this point, did they just believe whatever Palpatine told them?
The Clone Wars were used by Palpatine to prove that the Republic ("democracy") was ineffective and that stronger, centralized leadership ("dictatorship") was required -- that's how the Republic won the war, at least in public appearance. For example, Jar Jar Binks made a motion in the Senate to give Supreme Chancellor Palpatine emergency powers to end the Senate's deadlock over the Military Creation Act. This allowed Palpatine to unilaterally authorize the creation of an army for the Republic, and this had to have been seen as an effective yet dictatorial action when the clone army came to the rescue at the Battle of Geonosis shortly afterward.
At the end of the Clone Wars, everyone was war-weary and just wanted peace. They were willing to give up even more of their freedoms in exchange for this peace and security since the act of giving the Supreme Chancellor more power proved effective for the Republic in the Clone Wars. This is why Palpatine justified the creation of the Empire the way he did:
In order to ensure our security and continuing stability, the Republic will be reorganized into the first Galactic Empire, for a safe and secure society which I assure you will last for ten thousand years.
Star Wars: Episode III Revenge of the Sith