The main problem with this and how the overall story works out, is that while objectively true, the context and order of events matters.
^ and the false equivalencies rarely work out in Sam's favor, which I have always found perplexing given their efforts to flip the narrative and that Sam is supposed to be call #1.
Dean "if thats what it takes" has always put his issues aside in favor of keeping the family together. He says "because we're brothers" as some kind of cure-all because that is how it has always been used against him -not always by Sam, and Sam is apparently oblivious to some of it, but whether he asked or not Sam is the main benefactor.
Obviously John did it first, and I would argue his words echo strongly through all of Dean's decisions all the way through to the end of Season 5 before becoming more background character information, then Bobby's boo hoo speech after their fight in season 4 puts that on Dean (despite Bobby's own hypocrisy in a similar situation in season 6 I might add), then Dean is expected to put aside the damage done to their trust in season 5, he didn't blow up or send Sam away until Sam suggested it, and even though he didn't really want to he comes back after just one episode when asked and was shown yet again that Sam needs him, then Dean has to ride in the same car as the dude who let him get turned into a vampire, and after that problem is solved- briefly pretend it never even happened to protect Sam, then Sam threatens to leave if he doesn't put aside purgatory because Dean dared be honest about how that affected him, meanwhile Sam sabotages and takes Dean's other relationships personally. Whether Sam has reasons or excuses for these things is besides my point, because the fact is they had an effect on Dean, and (besides the times Sam walked away or asked him to walk away) he choses Sam every time because they are brothers, and spoken or unspoken, often the 'terms' of making it work involve just getting on with it without "guilting" Sam (even accidentally), giving Sam trust and responsibility regardless of whether it was earned back because that is the nature of their job, and going through the motions long enough for them to regain their old sense of Normal.
So of course he feels like this. It isn't fair, and it isn't healthy. But it is what he has always been asked to do, and what they have always done. In a way it would then be fair to expect the same accommodations in return (remembering that initially he did leave, understanding that Sam wanted him gone and needed space, and it was pure chance Garth's case brought them back together in aid of a mutual friend). IMO this isn't Dean not showing remorse, but just angling for more time together to be able to put it right because that's how they have worked through things in the past, whereas their history of splitting has been largely no-contact and if they split to hardly ever talk again how exactly would that 'fix' anything anyway?
Sam isn't responsible for John's actions, or Bobby's words, or Deans actions which are the reasons he is pissed. He isn't always the one who drags Dean back in in the scenarios I gave above, but he is surely glad that Dean did and he is aware to some degree what this means to Dean or he wouldn't have pulled the "we can work together or we can be brothers" crap on him. So while Sam's emotions are clearly sympathetic in this scenario it still comes across as hypocritical, because on some level he is aware of just how much "because we're brothers" has worked as a cure-all in his favor thus far. By saying "everything that has ever gone wrong between us has been because we’re family" he even accidentally mirrors their conversation when they split in Season 5, a split which is pretty quickly and definitively shown to be the wrong decision that Dean has to correct.
As far as Osiris goes I don't think that's a real indicator of remorse for either of them because its to skewed for Dean by his own self loathing and guilt, but while we're on the topic of Gadreel I do think it is important to note that Dean never actually says sorry for that, and he says sorry a lot. He gets up to it, but just trails off and doesn't finish the sentence, because while he's sorry Sam got hurt he's not sorry for his actions. It saved Sam's life and while he might like to change the details he probably can't guarantee he wouldn't do it again, how can he be sorry.
It has been a long time I made it all the way through 8 & 9 in order & without skipping bits and pieces because it is such a bitchy, dramatic slog to get through imo, so my memory might not be the best. Its pretty evident by this point that they just really suck at having them /show/ remorse and the good intentions to make a change (regardless of if it even makes it into the surface dialogue in the first place) because they are so focused on pushing the boys into the next storyline (and as much as Sam might say some variant of "what we were before was the reason for these issues we shouldn't just go back to that", that is exactly what the writers want). We need them to be over the last drama so that we can throw them into the new one, it makes it heaps easier for all involved if one becomes the catalyst for the next so of course we never really see any real resolution.
Instead we get the sweet moments in between to show us that they are all good, or little speeches like the one Dean made at Rufus's funeral to cover all bases - but overall we are left always circling back to "well you cant hold x against A, they've all messed up at some point". From an external perspective I'd be willing to put part of the reasons for Gadreel are as simple as the fact that it was Deans 'turn' to screw up, and they needed something real, because of the nuclear backlash they got about Sam not looking for Dean in purgatory. Throwing in the MOC was a bonus screwup doubling as a bone for the Dean fans as some narrative focus.