The specific example that made me start thinking about this was how AC Odyssey has a sidequest where a slave doesn't want to be freed because he thinks being a slave is cool, actually, which is both absurd apologetics but also misses that in Greek and Roman systems manumission was a form of social control that both rewarded and indebted slavers' most loyal collaborators. That turned into thinking about how just absolutely absurdly shitty classic Greek society was in general, and how AC Odyssey made it this weird wholesome egalitarian slaver dictatorship where everything's cool and good except for the bad mean guys who are indistinguishable in methods or goals from anyone else.
That's also one of the things that pisses me off about Starfield so much, how the "good guys" are a pair of far right colonial empires: one is literally just the fascists from Starship Troopers, and the other are a bunch of feudal ancap dictatorships. Even the villains are just saturday morning cartoon villains who are bad and mean but don't really ever do anything distinct from the "good" factions except be ontologically opposed to you, the main character.
Someone else pointed out recently how HOI4 ends up effectively doing Nazi apologetics the same way, where in trying to avoid giving their worst fans a holocaust button they just outright remove all the actual horror and material actions the Nazis did altogether.
And I don't think I even need to get into how rampant this problem is in liberal fantasy settings, which are always full of apologetics for monarchism, because that's well tread ground for criticism. It's enough to make something like how the original Mount and Blade handled the in-universe nobles as being inherently sexist and classist pieces of shit who were obstacles for a female and/or commoner PC to fight against and overcome almost refreshing, instead of it just being like "yeah these awful pieces of shit who are all definitely mass murderers and worse are actually cool and nice to you and not really all that bad really" like so much feudal apologia media does.
And yeah, there's a point to be made about not wanting to grapple with problematic themes and all, but where there's the line where that just turns into apologetics for the very problematic thing you're trying to avoid dealing with at all?
You bring up some good points and gave me some things to think about. My part was mostly subjective preference: I wasn't calling for forbidding shit worlds with shit people with nothing but shit possible in them forevermore, but I was saying I'm not going to be interested in them as entertainment if there's no one that I can be bothered to care about in it or at the very least have some sympathy with, or if there is such a person and everything they do is meaningless and smothered in the aforementioned shit for shit authenticity or otherwise in a totally-not-author-just-likes-shit way.
Sorry, that was my criticism of my own point, that taking it to its logical conclusion ends up pigeon-holing a lot of things into either just not being done or having to be bleak and depressing pieces, which is obviously taking things too far because as you say, that becomes uninteresting and I'd expand on that to say that if played fully straight, if one really dove into capturing every facet of the shittiness of say Rome or a Roman-expy that it becomes reactionary just by repeating and not combatting the sorts of chauvinist perspectives that would dominate such a setting.
So clearly there has to be at least some anachronistic or otherwise out-of-place good in a work, because otherwise one is just uncritically reinforcing whatever is being depicted (like how 40K largely fails as satire because it's just "things are bad and [bad thing] is correct in this context because [thermian propaganda]" a lot of the time, and relies on the reader being able to say "oh no this is bad, actually" instead of gormlessly lapping it up). But add in too much good and decency and it effectively becomes propaganda instead, like when feudal dictatorships get a liberal coat of paint in fantasy writing.
Which ends up back at what I keep trying to answer myself: where does one draw the line, how much responsibility does an author have to draw the line in the right place, are there tricks to streamline this and make it simpler to comprehend? And every now and then I have the horrifying realization that I'm like two steps away from suggesting "what if the Hays Code, but communist, as a bit?" which moderates the line of thought but sends me back to the drawing board, so to speak.