OK so like thinking about the finale and why I was never really bothered by it.
Now I don't think it's good, Spn getting good needs all the stars aligned and that's rare. It often has good elements but the whole is more than the sum of its parts yadi yada. So I'm emphasizing that this isn't me saying it's a good finale (covid restrictions means it's as good as they could do within how bad it was gonna be anyway). Because it's not.
The thing is that we saw Dean being suicidal over and over and over for 15 seasons. For 20/22 episodes long seasons. We've seen Sam going from not wanting to be a hunter to "accepting his fate" to not and on and off and it kinda became situational more than something he might or might not want.
The whole 15 seasons long thing is important.
Now the basic idea would be once Chuck's done influencing his story, the brothers are truly free to do what they want, whether it's being a hunter, going full domestic, becoming that weird mysanthropic uncle in the woods, or killing themselves. Ideally the brothers would get to heal. Ideally Cas being brought back and Jack being hands off means they could actually heal alongside their family instead of fighting angels and gods and dealing with full on apocalypses. And on a meta level we wouldn't get to see it because what we were seeing was because of Chuck. Kinda like how in Squid Game the audience has stand ins and it's the VIPs.
But we spent years, 15 years aka 1/6th of a century aka a month of watching if you watch it 8 hours a day, with them being hurt over and over and over again. Having ONE episode saying "yeah they got to heal but most of it is off screen".... I would have been so enraged out of frustration.
Also you could make the argument that if that were the case there should not be an epilogue at all.
Now if the seeds had been planted earlier I'd definitely be more amenable to the idea, the characters gaining bits of autonomy by learning how to communicate and heal together. But 1 season wouldn't have been enough imo and what we had at the end of the day, by season 11, was Chuck's story rather than the brothers' story.
Also this isn't a short series. Where you just have two(2) 10 episodes long seasons to conclude in 1 episode. It's 15 seasons. It'd be hard to wrap a 15 season issue for 2 nuanced characters in 1 episode is just.... It's not impossible but it'd require a level of writing Spn doesn't have bc it's not the point of the show.
So we arrive at the end and Dean's still suicidal. His reason to live was protecting Sammy (and his friendship/romance with Cas I don't care how you see it). Neither is needed now and you can say that he lasted a full on 6 months, he sure lasted longer than in s13 where he basically committed suicide within a month of Castiel and Mary's deaths. Probably bc they didn't have the weight of the world on anymore so he could actually try. Meanwhile Sam's still lost. Does the family life suits him ? Probably not but the guy lost his nuclear family and trying to recreate one the 'normal' way is something he used to want and it'd fit that he'd at least try it. He probably adapts to whatever the person he dates wants too.
It's not even really shown as a tragedy because at this point it isn't. The tragedy was what we saw for 15 seasons. Now no matter what happens it's good.
So it's lackluster, it's bad, but it makes sense in the context because Spn was often more about putting one foot in front of the other and enjoying what you can when you can and fighting to lose as little as possible but they never really explored what you do when you lost the thing that helped you do that (at least for the MCs... They kinda tried with the Harvelles and Jody but never actually committed to it) since their solution was to always bring at least one back (usually one of the MCs).
And in the end I think anything else would have really really frustrated me.
Edit: that's why John's there too. They never fully dealt with their issues so they can't go no contact with him even in heaven