On the side that decides on and pays for the offices, open floor plans are cheaper and more convenient. They take less space per person. You can moved stuff around and rearrange them. You don't have to decide on team sizes in advance. You don't have to allocate office quality based on seniority. Managers can get a feel for happenings just by being present. etc. Moving in does not mean a big upfront cost and it is easier to make the decision. These are price and convenience concerns. Those drive the decision most of the time. There are a whole bunch of arguments that can be used to justify the decision. knowledge flow, agility, egality, whatever. You can agree for disagree with them but they're not honestly making up a significant part of the decision so the argument is pointless.
On the other side are the people who work in the companies who mostly don't like open floorplans. It seems to me we don't like them for the same reason we don't want to live in a big dormitory. We want our own space. We want to control our environment. Same thing every 14 year old wants. We spend half our lives at work and we want a pleasant office for the same reason we want a pleasant home. More space is more pleasant. These are "quality of life reasons. This side has abstract arguments too. Quite. concentration. etc.
The whole argument is dishonest. One side wants to make life cheaper and easier for themselves. The other wants to make life more pleasant. Both are pretending to be discussing productivity, creativity and whatnot.