Threads like this usually turn into arguments about what was or was not a great version of Superman but I think your assessment is reasonable and not trying to provoke people who liked more recent movies.
I loved Superman (1978) alias Superman the Movie. It had a couple of flaws but nothing that stops it from being one of the all-time great superhero movies.
I had a few more issues with Superman II although most of them were in the last few minutes (hand crush/ possible killing of helpless opponent; petty revenge on trucker; Amnesia Kiss).
Superman III. Great Richard Pryor movie and I did like Annette O'Toole's Lana Lang although the relationship was of course doomed to eventually another Amnesia Kiss.
Attacking Superman IV is just too easy.
Call me foolish. Call me irresponsible. But I actually liked "Superman Returns". Oh, I'm not saying it was perfect. I may just have a different definition of boring than you do. I liked the dynamics of the situation Superman found himself in and I didn't have any need of some big super powered slugfest. Granted the choice he made that created that situation was ridiculous. Going to the shattered remains of Krypton knowing he would be gone for five years. I mean, he already left Martha Kent for twelve years presumably not knowing where he was. Then if only the first two movies happened, he comes back for a couple of years and then leaves again for five years? Man, call your mother. She's worried sick.
There were lots I liked about "Man of Steel". That Jonathan Kent "maybe" to me was just a guy caught in the moment saying the wrong thing but, with every fiber of his being, he was driven to protect his son. Keep in mind this is a more realistic setting. We can argue about that all day but it was basically a Post- 9/11 setting where paranoia is rampant, "If one of them did it, they all did it" (which is one of the very essences of bigotry), "All you towelheads get out of MY country" and where immigration isn't exactly the good thing it once was and a lot of people want even children who were born here deported. Not exactly a world that is going to welcome an illegal immigrant who has the powers of a walking Atomic bomb with open arms. So I think Jonathan Kent is justified in his paranoia.
The only thing that really damaged it for me was the overbearing destruction in the final fights that focused more on the damage and the CGI than on the hero trying to save people (as in the Avengers) and the fact that, inexperienced or not, Superman seemed oblivious to how many people very likely died when he, say, punched a guy into a freighter and it exploded.
But I think we need to define what we mean by a great Superman movie. I think going highly realistic has proven to be highly divisive. There are as many people who hate MoS as love it and even a lot of people who liked it aren't enthralled with it as they were with StM although I know some people are.
I think the WB and DC got locked into the fact that the Dark Knight movies worked so well and that dark is in while not considering that this may not work for Superman. Even those who love the movie cannot seriously deny how divisive it has been. It may also be that the creative people that currently were in competition to get to do a Superman movie are people who were raised on a very dark and gritty comic book world. While the current crop of comic readers may love dark and gritty, this may be a default because everyone else who doesn't care as much for it has stopped reading comics so the comic reading crowd may be badly out of sync with what general movie audiences want and expect from superhero movies.
There's also that it's Superman and probably no super hero is locked into a specific image of what he should be as much as Superman.
I don't think there's any magical formula. "Superman Returns" failed not because it imitated the Donner/ Reeve movies but because it imitated then badly. It felt weighed down for most people with a mopey, depressing Superman who didn't have the energy and, yes, the fun, of earlier versions though than fun should be tempered with seriousness.
Plus with every attempt, it gets harder and harder to get audiences to give it another chance. You can only retell Superman's origin so many times or do another Lex Luthor plot so many times. They could take a hint from Marvel. Introduce Luthor and kill him off (not by Superman doing it but kill him off) at the end because it's a movie. It's only going to have three stories or four or five at the most. Change it up. Give people the Superman they expect but don't let everything be what they expect.
The problem is it starts with the people who have the final say themselves understanding the appeal of Superman enough to put the right people in charge of making the movie and that's a major task right there that I have no solutions to.