There is nothing wrong with Ewoks.
They are barbaric, ritualistic bears that live in trees. They hunt and cook prey live, and even use guerrilla tactics. Tactics they use to take on an army eons ahead of their time. That takes true balls.
People say the Ewoks beat the empire, but they were in fact getting slaughtered left and right before Chewie managed to steal an AT-ST and change the course of the battle. Chewie was the key to the fight on the ground, Lando the key to the space battle, and Luke cut off the head of the empire.
The OT is probably the best science fiction trilogy in the history of science fiction. Having a bitter sweet ending to the extent some of the writers and actors wanted would of absolutely killed the franchises legacy, especially when you accept that they were targeted towards children just as much as adults.
This however in no way is an excuse for the absolute failure of the prequels, but that goes without saying.