Meanwhile, Lamar was dumber than a crate of bent hammers, but I gave ten times more of a shit about him than I did the protags. He got that Extremely Stupid Dog in him, and I can't hate that.
I only got about 2/3rds the way through the game before losing interest, but I have to say making all three protags unlikable was really something.
So you've got Trevor, a crazy psychopathic murderer so completely over the top that he makes the insane look sane. Some people find his antics entertaining, and I won't deny he can be funny at times with just how batshit bloodthirsty he is, but likable? Shit, I guess if you a real dumb sadistic motherfucker. He's a caricature and a critique on the average dipshit murderhobo player, as you noted. I suppose that lends him a degree of "art" core or whatever, but he's still a fuckface and I was actively rooting against him.
Micheal is a sleazeball. Like Trevor he's a caricature and a critique, but this time on both typical hypocritical gangsters and LA entitled rich boy culture. His wife is the same, only this time for gangster wives who give up their morality for material wealth. His son and daughter are useless dipshits, but really they were raised in a place that basically made them that way. Micheal pretends to be some kind of professional but in reality his life is a mess and he's about as sloppy as they come. He too is over the top but in a more sleazy way and a less "kill or fuck everything that moves" way.
Franklin isn't a caricature, and is probably the most likable of the three, but all his motivations are just greed. He just wants money, and out of the hood. I don't blame him for wanting out, of course, but it's not like he's a good person.
On the other hand, Lamar is like if Franklin was a true ride or die homie. He's a big idiot, and he's violent as fuck, but I can't hate him because Big Dog, Big Nuts. Really one of the only genuinely likable characters in the whole game.
It's really weird to me coming back to GTA5 after playing RDR2, and just seeing the stark differences in how the characters are written. But then, GTA has always been a parody series. The characters in RDR2 are, full stop, the most fully realized and best written characters I've ever seen in a videogame. There's some small elements of parody in the RDR series but for the most part it takes itself seriously. GTA does not, and the characters end up as stupid hollow pastiches because of it. GTA5 I think just pushes this angle far more than any GTA game beforehand. Tommy from Vice City was a criminal who spends almost all of his time killing people, but he's not really a joke character. He's more like Franklin in that everything he does is motivated by greed.
Meanwhile Arthur, the main character of RDR2 is a legitimate exploration of a human being. He's an outlaw and a killer who robs people, but he also likes helping people. His whole story arc is about that and him finding out who he truly is under everything else. The game asks "what is Redemption" and if it is even a thing that can be attained. And it doesn't answer the question for you.
And that's just Arthur. Every single gang member is almost as well fleshed out as he is. I have said to my friends before that you could take RDR2 and make it into a high quality TV show, and keep basically everything the same, characters and story. And I would lay 10 million dollars that all the sudden all the critics would fall all over themselves talking about what an amazing character study it was, how all the acting was top notch, etc. But because these characters and story are all trapped in a video game, 80% of humanity will never know that they even exist, much less their quality. It really is a shame.
People generally point to games like Shadow of the Colossus or Papers Please or Cosmology of Kyoto (if you're Roger Ebert) as proof games can be (or are) art, but for my money it's RDR2. Both because it has the best characters and story of any game, and it's also just a traditional game game where you shoot a lot of dudes and level up your skills and shit. It proves that you don't have to be all artsy fartsy or hyper-alternative to be really great art.