Do the members of the rebellion believe in the republic or merely in the fall of the Empire? The protagonists of the first trilogy never seem particularly interested in re-establishing the republic: sure, it’s what they’ll do, but it’s not their mission. Their mission is the destruction of the Sith, and it’s here that another big clash with the prequels can be found. In the prequels, the Jedi are explicitly tied to the preservation of “democracy” (a word you won’t be hearing in the original films), whilst in the original films they are simply there to fight evil. In other words, the mythos of the first films is simply Good Vs. Evil, whereas the prequels attempt to establish a complexity of political belief.
Here’s the problem, though: if the Jedi are supposed to defend the republic rather than fight the Sith, they give in at the end of episode 3 far too easily. Yoda could have gone back and won that fight, or at least tried. And did Obi-Wan do nothing on Tatooine AT ALL until Luke brought him an R2 unit he claims not to remember? Yoda and Kenobi’s retreat into hiding only really makes sense if their mandate is to defeat palpatine rather than to restore the republic – another place where the transition from episode 3 to 4 is clumsy at best.