I see what you're getting at but everyone being happy doesn't necessarily mean all is well. It could be that in their selfish desire for their ideal ending they forsake something else. We don't know whether it's a truly perfect ending in every sense of the word yet or not. Also I wouldn't say that the original ending would be reduced to being something that occurred due to Noctis' own foolishness. It's simply one where the gods and prophecy were valued more.
It's true that the "super happy ending" doesn't have to be treated as an ideal solution and it could require the sacrifice of something else of value. My concern is that that's not how they're selling it. And I don't think that allowing the difference to simply be the amount of value the characters place on the gods and the prophecy really works if there's no practical benefit (whether physical or spiritual) to valuing the gods and the prophecy but plenty of practical benefit to being defiant.
A prophecy that only exists due to their initial failures. If Noctis succeeds or fails by going off on his own the crystal and gods end up wrong either way cuz what they foretold didn't come to fruition and it wouldn't be the first time seeing as Ardyn was their first failed attempt at creating a savior. The crystal told him to go heal everyone only to later demonize him.
Well, my issue is less with the idea that freely willed human actions can interfere with the outcome offered by the prophecy and more with the idea that the solution offered by the prophecy could be one-upped by the characters rejecting the only known solution and succeeding because the rules of the universe literally change to suit their whims (I'm looking at you, FFXIII). If they wanted to make an alternate ending where Noct tried to succeed where Ardyn had failed and caused a catastrophe, I wouldn't necessarily have a problem with that.
The gods also have plenty of other moments of bad decision making and moments where they lack morals in FFXV such as Ifrit giving Solheim technology only to get mad at them later which prompted Bahamut to smite him since he was going to burn humanity to a crisp, Leviathan also wrecked Altissia for no good reason and is the reason Luna was even put in the situation that got her killed or why Ignis had to give up his eyesight at all, then there's Shiva who used to freeze people all the time as well until she fell in love with Ifrit according to her own backstory.
I interpreted the original ending not as something that occurred because the Astrals concocted this perfect plan that would go off without a hitch but as something that happened because this time around they got lucky that they didn't create another Ardyn which I entirely attribute to the bros keeping Noct in line through their unconditional friendship. The gods in this universe aren't infallible or all powerful which puts them more on par with the greek pantheon which is built on the concept of flawed deities. At this point we're just debating our own interpretations I guess but I do personally believe there's far more evidence in XV that proves the gods aren't perfect than there is to prove that they are meaning that it's entirely possible their plan wasn't the only solution after all, just the solution that best worked in their favor.
Bad decision making and lack of morality is true of the elemental Astrals, who basically reflect forces of nature, but Bahamut seems significantly more stable than the rest of them, and he's the one who came up with the King-and-Oracle plan. He's more like an archangel than a theistic god, granted, but I'd much prefer that he remain essentially good and noble within that role, even if he can be wrong (say, in putting his faith in Noct even in an ending where Noct's disobedience leads to catastrophe).
Anyways while I don't agree with it and have my own interpretation I respect your interpretation of what FFXV's ending meant as well. We'll just have to see ultimately how things end up once we get to that point. I also get the feeling you took some of my statements as attacking your faith which was not my intention so I'm entirely sorry for that as well if it came off that way.
You don't have to worry that I took your statements as an attack on my faith. My frustration is entirely with certain cliche ways in which fictional works (particularly JRPGs) set human agency and freedom over against religiously-charged supernatural beings that want to keep them down, not with anything specific to the discussion we've been having.