I've definitely seem benefits from working in open plan. Sometimes it's helpful to overhear what others are doing because maybe they're lacking some information or maybe that thing has already been done elsewhere. Does a fresh graduate with no experience really want to be in an environment where everyone is shut in an office?
Equally, sometimes it's better to be quiet. Sometimes, quiet can be at home but sometimes homes are not quiet or uninterrupted.
Flexibility would be great, but I think a private office will always be seen as more prestigious, so those with that facility are unlikely go give it up so sit in a cube / open plan with the team, even where that would actually be beneficial.
Equally, sometimes it's better to be quiet. Sometimes, quiet can be at home but sometimes homes are not quiet or uninterrupted.
Flexibility would be great, but I think a private office will always be seen as more prestigious, so those with that facility are unlikely go give it up so sit in a cube / open plan with the team, even where that would actually be beneficial.