@amagire I'm now realizing that I both did and didn't misread that scene; Jedi starts out setting up Luke going in Vader's direction, so "killing the Rancor has implications" fits into that.
But as a kid, I *only* saw "exciting fight with giant monster and funny joke where the big mean guy is uncharacteristically upset."
The prequels show that Lucas simultaneously *can* try to make a nuanced epic story and a kid story. Lucas is an okay storyteller but not good enough to really pull that off.
@amagire the embarrassing part here is I thought the guy being fat was part of the joke (since I was a kid when I first saw Ep VI and fat jokes were all OVER the place then). So maybe him being a fat dude isn't a joke, but part of the larger "he's a big mean dude" which was simultaneously supposed to be a kinda mean spirited kid joke/horrifying indictment of Luke going to the Dark Side.