From that list, I think point 2 is another thing that we haven't discussed in regards to RotJ sucking: The tone is inconsistent.
The ending of ESB sets up the third movie to be pretty dark, and indeed, it starts out that way. . .until the FUCKING EWOKS show up. It's so jarring. Everything else in the movie is relatively dark, except for the physical comedy ass-kicking teddy bears. I understand not wanting to make a movie TOO dark, but the ewoks don't balance the "darkness," they are downright saccharine and feel completely out of place.