I never saw JR as a villain. I see him as an antihero. I see Cliff as a villain who is trying to bring down the Ewings because he's jealous of what they have. Cliff doesn't want to admit jealousy is his motive so he says he's doing it for Digger but we all saw Digger say he never wanted to see the Ewings broke, or down and out, and Cliff didn't care what Digger had to say. Cliff just went right on saying "Well, they're gonna be flat broke..." Cliff never could admit to himself that Jock didn't destroy Digger and that Digger destroyed himself because he was a weak man.
Ellie would have known. She was right there at the time of the disagreement between Jock and Digger. Ellie cared a lot about Digger; they were good friends! Still, Ellie said "Digger would have ended up the way he is even if there had never been a Jock Ewing."
Also Sam Culver said to Jock about Digger "You did as right by him as anyone could have. Of course I could have done it without making him my enemy." Jock replied: "That's what makes you the best politician in the state."
"Katherine hated Cliff because of him embezzling her father’s company and causing Rebecca’s death by her going in his place on the Wentworth jet" Rebecca died because a pilot, or both pilots those planes made mistakes. Rebecca wouldn't have been on that plane anyway if she hadn't been sticking her nose in something that was none of her business. How much can you expect of a woman who would abandon her two babies, leaving them in the care of an alcoholic?