And all it takes is two chatty hires to ruin it (as a chatty person, I'm fine unless someone encourages me). If they kept a lot of private meeting rooms when they changed the floor plan, you have a good chance of convincing the chatty people to fuck off to a room if they want to talk, but most places don't do that. They use open floor plans to reduce costs, and then there are shortages of meeting space, kitchens, ventilation, and bathrooms.
The sales pitch of sitting in a group is that you can ask people questions and get an answer, but it's based on bad information about recovery periods after task switching. And as a lead I've been crippled by the inability to get candid answers from junior and midlevel engineers, and being unable to negotiate agreements with senior engineers by hashing out our disagreements in private where I can steer the conversation toward addressing their personal concerns instead of general ones. We should be concentrating on finding a compromise or promising more functionality so they're happy, so that it's two or three advocating for an idea when it's time to discuss it as a team. Instead it just gets shit on while I'm stream-of-consciousing it in the middle of a bunch of myopic people, leading to more confirmation bias and reaffirmation of the status quo.
[Edit] And good luck healing a rift between QA and dev if the QA folk have to wander into the lion's den to talk about an issue. I have only been a lead once in an open office plan (working on #2), because half of my skill is in knowing more about what's going on by liaising across functional or personality boundaries. Half of the rest is in fixing unidentified pain points, which often requires hearing from people who don't like to be a bother. Open plans don't encourage candor, they crush it like a bug.
Steve Job's line, as reported by Jonny Ive IIRC, about ideas being fragile and needing space to grow really hit home when I figured out I'm doomed to be in open offices until the pendulum swings back.
I currently work in the former environment (but everyone is like that guy), and it's super noisy and distracting but also fun.
It is more fun though, to have a constant debate. Just not productive.
I used to work in a small open office where one guy would constantly hold debates with everyone. It was pretty hard to stay out of it, and very distracting.
Now I'm in an office with a similar layout and staff, but it's like a library. There's the occasional group discussion or banter, but not enough to bother.
I've worked in finance my whole career, so it's all open plan, lots of screens. Never had my own office, people always needed (well so they say) to be accessible.