I don’t mind the existence of Ewoks, I really don’t even mind much that their victory is somewhat implausible. I understand why someone wouldn’t like them, but I never minded them. The problem is that too much focus is on them, and the scenes on Endor are interspersed between much better scenes (Space Battle, Final Duel). The scenes don’t flow well into one another. If the Endor scenes were more brief, and they found a way to include them without jarring tonal shifts, it would be right up there with SW(ANH) and ESB.
In my edit, the Ewoks are less cute. During the battle this is how it plays out. The reason I put this in this thread is because it highlights exactly what makes ROTJ lack enough of a punch in its third act.
-There’s an outbreak. The Ewoks pop up and start shooting arrows
-Everyone scrambles, Leia shoots a trooper, Han throws one over his back
-they retreat to the bunker, the empire backs off too for a shootout
-Leia needs R2 desperately
-we cut to the Ewoks pitiful catapults get blown apart as they run away. An ATST blows down tree after tree then we cut to space battle ravaging outside the moon.
A little bit later…
-Lando has “gotta give him more time” (Han)
-we cut to Endor. No Ewoks trample on storm troopers from behind. C3PO’s “were coommming” is cut. We jump straight into the action minus the Ewoks.
-R2 takes a hit. Han tries to rewrite it himself.
A little bit later…
-no Tarzan yell from chewie
-heavily cut the scene where they take over ATST.
-the “I love u” “I know” callback is gone.
All of these cuts leave you with a much more focused, contained and more intense finale where you don’t spend as much time with the Ewoks on Endor and when you do its just shown as a desperate battle.