The sort of Stringer Bell-hate you see among people talking about the Wire these days is interesting, because it is also a broken pedestal thing.
For the first season of the Wire, Stringer Bell is THE narrative hook. The first season has as its premise that they're trying to chase down a new generation of gangsters, who not only operate with more secrecy, but more brutal violence - killing witnesses. And though Avon's the actual kingpin, we the viewers are told that the mind behind this strategy really seems to be Stringer Bell: he's who our (White*) POV protagonist immediately fixates on. The narrative tells us that Stringer Bell is the stand-in for the new generation and its way of operating; the carefulness, the violence, all of it. He's directing the details, the stuff that gets us interested. He's the vizier, officially, and in reality, we see time and again him deferring to Avon, but he's the one who is moving the chess pieces, he's the one who gets away at the end; he's the Villain.
So, when later seasons show him ending up failing to ascend out of his station, viewers now a day seem to think of him as essentially just a scam, or, like you write, somebody who thought he was too good for what he was. But it is that ambition that makes him so compelling a threat in the first season though; the viewer shouldn't view it as a look behind the curtain, showing the real, incompetent Stringer Bell, the viewer should look at how all that ambition and violence cannot transform his social station, despite it serving many people in the social station he's trying to ascend to.
And Bell does succeed in transforming the drug game, for the kingpin types at least, with the co-op. The co-op is the last piece of Bell's genius, and a lasting change we see survive him. Now, it's not really a social good, except in so far as it keep the inter-gang conflicts down: they still prey on society's most vulnerable, and murder and kill. But it is a transformation, and I think a lot of people would argue that sort of capital cartelism is still a social good, at least compared to outright gang war.
But he can't approach the people on the Clay Davis' level, the real institutional players, not like he can the other drug kingpins. Avon tells him that's all away-games, and that they should stay put, essentially. Avon also dislikes the coop structure and ends up sabotaging it from jail, albeit for profit.
I feel like the same people who hate Bell also give Marlo a fair bit of credit. Marlo is of course the next next generation, the worsening (fiercening) of the that spiral. Like McNulty says, Marlo's MO is like that of a serial killer. And in contrast to Bell, Marlo gets that high life, he gets to transform. A key contrast there though, I'm just thinking of, is that Marlo lets his lawyer, Levy, handle all the financial stuff right? Whereas Bell pointedly didn't, he wanted to cultivate his own connections - maybe you could connect it with his Black Pride youth, that he wanted to work with a Black politician to do it, I really don't know enough of that to say.
In any case Bell cannot ascend, without being allowed by the money-men to do so. Maybe it's because he can cooperate with the other drug-kingpins because they're socially the same - they can all take out a hit on each other if they don't trust it, leading to gang warfare. If he kills Clay Davis, like Avon points out, all hell will be brought down on them - they'll be as powerless against that, as William Gant was to them. Bell cannot ascend as an equal on those kinds of terms, he can't completely transform. From Gant's POV, or Wallace's, all this would be fitting karma. But the discussion online I see isn't really about that, it is, like you say, that Avon and Snoop and Chris and Weebay were good soldiers.
But for all Avon "knew what he was" or whatever, he ended up in prison, his connections on the street quickly disappearing. His insistence on "just being a gangster" is as suicidal as Stringer Bell's dreams were delusional. The spiraling of the Baltimore drug game seems to always swallow all the local players**, big or small, while the suppliers remain the same. For all people talk about Weebay being a good soldier, Weebay's last thought on it is that it landed him in prison for the rest of his life, and if his son could be anything else, shouldn't he? Wanting something else, the thing Stringer Bell wants, is crucial to not getting stuck in the spiral but requires a hell of a lot of luck, as we saw with the one s4 boy who got out.
So yeah, I think people are gleeful about an ambitious character trying and failing to ascend from his station, for all the reasons you wrote, but the reason they talk it up so much is also because of the cracked pedestal: for a moment the narrative presents us him as somebody truly changing the way things are down, a real transformational figure; but the rug-pull for the audience, isn't that he's not a transformational figure, it's that that sort of transformation just isn't possible for somebody like Stinger Bell in the kind of place he is from. All that power he, or Avon, or Marlo crave can come only with great violence and only at the mercy of their suppliers and lawyers***, the systems boxing them in.
*our Black POV protagonist in the first season, DeAngelo, of course also ends up in an oppositional relationship to Stringer Bell, and is killed for it, which strengthens this sense of Bell as the Villain.
**except that one really old guy on the co-op, guess he's got it sorted.
***I'm overstating this. Obv. there are examples of gangsters going clean successfully while keeping their money and power, and I'd hardly call it good that they did so - then again, I don't know that there are that many Black American gangsters that have done that, as opposed to the White ones.
