> "you can overhear the spontaneous decisions during the day"
This is a good thing if the spontaneous decisions are always and only the ones that are important to you. This is a bad thing if there is any other decision. In a shared multiple companies space the only decision that matters to you is "where should we go for lunch" (they might not work with you, but you can still eat lunch with them). In a company only space it is better, but there are still a lot that don't matter to you. If it is a team only shared space most of the decisions matter to you.
When I was working in a startup, we did a "hybrid wfh" thing: we knew when we were about to have something requiring our full attention and would work one (or multiple) days from home. We had Google chat (or whatever it was called at the time) for anything that could handle a delay in response and the phone for anything that needed a chat right away.
At the time, the office was in a kind of co-working space, so it was a particularly hellish combination of open-space and multiple companies, complete with people unaware of their phones' silent mode. The upside was that even for regular work, productivity skyrocketed when we were home, so the founder, who initially was against this, started warming up to the arrangement.
More broadly, I think that different jobs have different requirements. I hate it when people talk around me and find it harder to focus. I never got used to this even after multiple years. And while I love listening to music, even while working, I don't enjoy wearing headphones all day long. I'm wearing glasses, so bigger headphones start to hurt after a while and in-ears are pain to put back in after every interruption.
Also, headphones cut you off from the surrounding discussion (that's the point, right?) so the whole "you can overhear the spontaneous decisions during the day" kinda falls flat, doesn't it?