Having a big ego doesn't necessarily mean demanding your character prevail in every scenario. At one point, Larry even suggested to Katzman that JR "lose everything" because Hagman thought it would make a good storyline.
People's egos work differently, and you can have a big one without being totally subjective.
That's a possibility, as counter-intuitive as it is. I have never been in the acting business so I certainly can't say their egos don't work that way.
The thing that makes it seem kind of unlikely to me is that with an ego problem, people tend to want to be the center of attention and are not too .concerned with anyone else. So the opposite of that - being generous - is to give to other people. To think: I'l allow my character to get humiliated by Sue Ellen and that woman who just joined the show,the Creider woman, both make me look like crap so they can look impressive and smart and all of that, because I want to make sure their characters get respect from the audience" - Honestly, that sounds pretty generous of him to allow their characters to get the benefit of having foiled him and achieving their goal, while JR is now somewhat diminished in the eyes of the audience -" maybe he's not as smart as we thought." This are generous actions, and I can't say I've ever heard any complain about anyone with a big ego: "When his ego gets big, he has no regard for himself because he's so busy giving to others, he's just too generous"! That goes against everything I ever read about human psychology.
So while I'm not sure about that, here's something I do think is very accurate: Larry Hagman was given an executive position and his response was he didn't know anything about how to do that -he was an actor. They responded: Don't worry, you won't have to actually do anything, and the job-title means your paycheck will be bigger." OK, I'm being offered a bigger paycheck with no added responsibilities; who would turn that down"?
I don't expect anybody to turn that down, but from other things forum members have posted, it turned out they actually did give him some new responsibilities regarding storylines and the directions in which they were taking his character and others. Larry Hagman was a brilliant actor, and remarkable at coming up with quick ad-libs for JR to say. He wasn't a writer though, he didn't know how to help produce a show and he even said so but Katzmann gave him writing and producing responsibilities anyway.
If anyone was "destroying the show" as an earlier posts claims Hagman's ego was, I blame Katzmann for taking someone who isn't a writer, doesn't claim to be one, or even want to be one, and lets him dictate when his character is going to prevail and when he's going to fall flat on his face. When you've got one of the most popular TV characters fall time on your show, you have to treat it seriously, because it's such a valuable commodity. People don't like JR because he's nice; they liked him because he was so good at what he did. They were impressed at the things he could get done witch nobody else could pull off! How can you risk having that character and its value tarnished, because the actor thinks it would be amusing to slip on a banana peel and then wink at the audience?!?!
You've got a character who became the biggest star on TV, a character who the audience things is one cold, calculating, SOB - a badass in the boardroom, and you're going to let him look like a clown because he thinks it would be amusing??? Just to give him laughs during his "day at the office"? Whoever allowed that to happen, whoever thought Hagman could and should make those decisions and then gave him that particular the of responsibility and creative control, that's the person to blame!
If Hagman were phoning in his perfromnces(which he never did, even in the worst seasons), that's on Hagman. If the executives put Hagman in a position of a writer or producer - that's on whoever had the dumb idea to give him that job.