I think the fundamental idea of the Ewoks, a primitive tribe getting the drop on a more advanced force and using their knowledge of terrain to defeat them, is not crucially flawed.
But it would have worked far better if they’d gone with the initial draft and used Wookies.
It was apparently not financially feasible. I don't know what the exact issue was. But as far as plot is concerned, you're certainly right. I've suggested the same thing, as have others before us. my suggestions (somewhat edited since I first posted them a few years ago):
— The film opens, not with the droids, but with Leia's attempt to save Han. This fails, as in the actual film.
— We then cut to Luke on Dagobah, completing his own light-sabre. This indicates he's been there for a while, training, with Yoda teaching him how to be a Jedi. Vader calls out to him through the Force, urging Luke to join the Dark Side, much as in one of the actual deleted scenes for RotJ. Luke resists, which proves that he has the mental power required of a Jedi.
— Luke is preparing, so that he'll be ready to rescue Han from Jabba's palace (unlike his half-cocked rescue attempt in ESB; we see he has learned from his mistake).
— Yoda dies. It's made explicit that Yoda feels that he is being called to become one with the Force, and that it is now time for a new generation to assume its place of responsibility in the galaxy. He tells Luke that
he (Yoda) has nothing left to teach him (rather than Luke "needing no more teaching"), and implies that the wise never stop learning. Now it is Yoda's own time to learn a greater mystery: he passes peacefuly into the Force. Luke, his training as a Jedi Knight complete, departs from Dagobah.
— The film then shows us the Imperials preparing for a committee of the Grand Moffs with Vader and the Emperor. The Rebels have become more bold since the destruction of the Death Star, and the previous attempt to definitively root them out (such as on Hoth) have failed. It's time to set in motion a campaign to wipe the Rebellion away completely. The Emperor is willing to allocate all means necessary to this, and will hear the suggestions of the Grand Moffs at a secret conference to be held on a space station orbiting the forest moon of the gas giant Endor. (This is an out-of-the-way location, and ideal for such a secret meeting.)
— No second Death Star is at any point involved. Imagine the space station more like a super-sized version of a
Golan weapons platform.
— We cut to Tatooine. The droids arrive, and are "given" to Jabba by Luke, via hologram. (Threepio, upon seeing Leia enslaved by Jabba, can exclaim something about how he "just
knew they should have waited for Master Luke!" or something to that effect.) We see that Lando has sneakily infiltrated the ranks of Jabba's guards already. Then the Twi'lek dancer tries to kill Jabba, and is thrown in the Rancor pit.
— Vader arrives on the space station and threatens Moff Jerjerrod. Everything has to be ready in time.
— Luke arrives at Jabba's palace. I'd tighten up the whole Palace sequence a bit, so that it drags on a little less. In particular, Jabba's 'court' and all of the bizarre figures there can easily be toned down just a bit. Make it less 'The Muppets', and slightly more serious and threatening. No silly musical numbers!
— Han should get his sight back in time to fight Boba Fett on the skiff, which ends with Boba Fett getting shot and falling into the Sarlacc pit. (But this could and should be a really cool gunfight.)
— After the rescue of Han, our heroes go directly to rendez-vous with the Rebel fleet, where Mon Mothma tells them about the Imperial conference. Thanks to many brave Bothans who gave their lives to get this information to the Rebels, they now have a chance to strike a critical blow at the Empire: killing their entire high command in one fell swoop. It's a unique chance, and all the more vital because if the Imperials instead get the time to prepare a greater anti-rebel campaign, the Rebel Alliance will almost certainly be destroyed.
— Arriving on the forest moon, must destroy the shield generator protecting the space station where the Imperial leaders are gathered. They discover the moon is used as a slave labour camp, where the Imperials are using Wookiee slaves to mine valuable resources. (They're slavers
and they're strip-mining a nature preserve! Pure evil!)
— Chewie can play a key part in helping the heroes infiltrate the Imperial camp. Since Han once risked his life to save Chewie, they can convince the Wookiee slaves that the Rebels truly want to help them. A slave reolt ensues, and lots of Imperial guards get their arms ripped off.
— Thing go largely the same, with Luke going to confront his father after telling Leia the truth. Palpatine gloats to him that the whole conference isn't a meeting to decide on a strategy against the Rebels: it
is the strategy, because it's a trap.
— Through a hard-fought battle, the heroes down on the surface get to the shield generator... only to discover an additional cohort of crack troops waiting for them. A desperate battle follows.
— The Rebels fleet arrives as planned, only to find the station's shields still active. The station is also far better-armed than expected. (Palpatine gloats that while it's no Death Star, it has cannons that can blow up capital ships). The Rebel strategy was actually to bring along Interdictors to stop more Imperial ships from arriving, but Palpatine has the Interdictors blown up first.
— Immediately, an Imperial war-fleet jumps out of hyperspace to ambush the Rebels. A massive space battle ensues.
— This plays out pretty much as in the actual film, with Han, Leia, the Rebel ground forces and the Wookiees eventually destroying the shield generator. In space, a few Rebel pilots in smaller ships (the Falcon, piloted by Lando, and a group of fighters led by Wedge) can get past the large Imperial ships and fly into the bowels of the space station. (I imagine it still-unfinished, much like the DS-II.)
— The throne room duel plays out exactly the same, with Luke then taking his father's body back to the surface (after getting off the station just in time). The Empire's high command is utterly vanquished, leaving our heroes hopeful for the future. I'd otherwise keep the ending just as it is (except with Wookiees instead of Ewoks, and with
no 'special edition' shots of celebrations on other planets).
