The trading day is also, I'll note, only 6.5 hours long. And people who don't get 25% raises (or more) per year leave. It's a stressful job and unless you're making $750k+ after 6-8 years in, it's not worth it to deal with the negatives of being on a trading floor.
Open-plan began to go into vogue as a backdoor mechanism for age discrimination, due to studies showing that older people were quick to associate them (and visibility from behind) with low status and therefore leave. Two decades later, I doubt the intention behind tech companies using these plans (and almost all do) is so negative as that. I don't think there's any negative intent anymore; it's just something that's done because (a) it's cheaper, (b) it's more tolerant of rapid growth, and (c) it's how things have "always" been done.
As long as people can step away without stigma or punishment, I don't think that open-plan offices are inherently evil. The problem is that few offices have enough quiet space to allow for that.
As for "the extrovert ideal", I don't know what to do about that. It seems to be human nature. People with families, non-drinkers, introverts, women except through the immense effort needed to be socially available but not seen as available in other ways... are never going to be "the cool kids". What I've learned, though, is that while "cool kids" get a quick start, they don't hold it and "cool" doesn't last. It's not useful to envy them because, while they may appear to be moving fast at one time, the 5-year picture is not especially desirable.