Okay instead of using quotes, I'm just going to put stuff in bold and hope you get the idea.
On the Avengers model vs. the Justice League model
I still think there's some disagreement here on what I mean. I completely understand where you're coming from, but you're still talking about "how the Avengers did it" vs. "the Avengers model." The Avengers model is simply "Do a movie for all the main characters, and then do a movie where they team up." Man of Steel, in effect, followed the Avengers model. So did Wonder Woman. So did Iron Man. I know you don't actually like Wonder Woman, but they all followed the model of "tell a story about these people."
I agree that Avengers gets bogged down in setting up sequels, but that's not really what I'm talking about. The First Avenger doing too much to set up the Avengers isn't a problem with the model itself - it's a problem with the movie itself. If they'd done a "Man of Steel" film for Aquaman/Flash/Cyborg, you'd agree that that's better, right? Because that's what I'm talking about. If we knew these characters before we came in, we'd be more invested in what's happening. Wonder Woman drops Steve Trevor's name without an extended flashback sequence because we know who he is. The Atlantis/Barry prison/Victor and his dad scenes would've had a lot more weight if we weren't learning who they all were on the fly.
I feel like, because I watch the Flash, I pulled some of my emotion from that for the Henry Allen stuff. For the Victor stuff....well, I just had to look up Silas Stone's first name so that's one problem. I also know they cut a lot of the Cyborg stuff out, but you don't think he was in desperate need of a movie?
I said a long time ago, but I think WB could've made a cool movie where they introduced all three new heroes. Sorta like a grindhouse movie. Three 30-45 minute adventures setting everyone up. It'd be super-unconventional, but at least we'd know. Even if they did an in-universe animated movie like "Gotham Knight" (before The Dark Knight was released). Give us something.
It's like the Atlantis scene - you make a couple different theories on why the air bubble is used. Imagine if, in Avengers, there had to be an extended sequence in Asgard so that we could understand where Thor was coming from, where he lives part of the time, who Odin is, how he can send Thor to Earth, what Loki and Thor's relationship is.....it'd bog down the movie. They can explain certain things because we've been to Asgard. We've seen Thor and Loki, how they grew up, and how they fell apart. We've met Odin and know about his magic. You can just catch us up with a line of dialogue.
The Flash
I'd completely forgotten about the Suicide Squad cameo, but looking back, it feels out of place now. Barry seems, at least to me, like early Clark on Smallville. The convenience store robbery seems more his style (and he was able to do that without his clothes burning off). I rewatched the cameo, and it feels like a post-Justice League Barry. Someone who's proved himself and has more confidence.
I know there's a difference between fighting a regular guy with a boomerang and alien monsters, but Barry (in Justice League) really flips out at the idea of even being on-location for the fight with the parademons. He doesn't seem like the kind of guy who's been a hero long enough that he does quippy one-liners when he's with Digger Harkness.
Again, if we'd had a Flash movie before, we'd know more about his character 
Steppenwolf
He's not as bad as everyone is saying, but he was completely one-dimensional villain. Another gray CGI person with no personality. The only thing he brought to the table was that he was good enough to fight the heroes on his own.
This is another problem with having to spend so much time introducing characters - your villains suffer. I don't even know if the movie would've had time for a character with any sort of backstory.
I don't think the movie was necessarily hurt by a bad villain (I like tons of movies without charismatic or interesting villains) because he was simply a catalyst to get these guys to work together....so, in that sense, he "fit the story" - but I can't imagine you're actually saying that Steppenwolf is a good villain by any means.
Bat-Family
The problem with "it might've happened off screen" is a huge problem for this character. This is Bruce's family. We got to meet Aquaman's family and Barry's family and Victor's family. A huge part of this movie is about how Diana closed herself off because she lost her family. A huge part of her story is about how desperate she is to get that back. Superman is brought back because he has connections to other people.
If Dick Grayson is alive, Bruce has to make that call on screen. Commissioner Gordon is in this movie. Bruce has to call the man's daughter, if she's alive, and tell her that the end could be coming. Same with Tim Drake, Cassandra Cain...all of them. Again, Bruce goes on a suicide mission in this movie. He expects to die. Calling his family, on screen, is *crucial* to rounding out his character.
There's a moment in Max Landis' retelling of the Death and Return of Superman (I know he's got his own problems now and is probably a garbage human but get passed it for this point) where Bruce is about to go on a suicide mission, and Dick realizes that his father is about to die. Dick swoops in to save Bruce before he does something stupid, fighting Bruce to make sure that he doesn't get himself killed. When Dick looks down and says...."Dad....", it makes me tear up every time. Imagine if Bruce had called Dick as he was driving toward certain death. It would've added emotional weight.
No one called Bruce when he was fighting the darkness in BvS. Bruce doesn't call anyone when he's confident he's about to die. If there's a surviving Bat-Family, they're too torn apart to ever come back together and don't need to be mentioned again. It's going to do irreparable damage to the characters.
On BvS Revisionist History
Its hard to really explain because I think the movie wants to treat BvS like it happened....the way you saw it. The only problem is that it didn't happen that way for me. Bruce keeps talking like Superman was a beacon for hope, but he was literally on trial for murdering civilians. He was hated by many for what happened in Metropolis. Bruce literally tried to murder him in the previous movie.
Superman's heroism and sacrifice might've been what eventually saved Batman, but it wasn't Superman's "beacon" that brought him out of the darkness - it was a coincidence.
I think BvS did revisionist history too. We've talked for pages about how I can't imagine that Superman did enough to be universally loved in Metropolis after what happened at the end of Man of Steel. it seems crazy to me that he'd have a statue that wasn't constantly being protested at.
Justice League wanted us to think that Superman was a loving, charismatic hero who was universally beloved when, on screen, he should, at the very least, be a very controversial figure who *tons* of people would be happy was dead.
Zack Snyder, at least to me, is showing me one thing and telling me another.