So, picture this. Two different types of offices. Office A has rows of individual desks with personal and private space, lots of items, and partitions or cubicle like setups. Office B is a singular large table with multiple chairs, people of all working levels, all sharing the same materials, and not much private space at all. Which office would you say would be more efficient? More productive? Which would have higher work satisfaction?
This is what I would wager, and I would love for you to tell me your side too.
Why? I can give your three reasons.
When everyone, including bosses and subordinates alike, sit in close proximity working, it is easy to monitor and check an employees work progress, habits, behavior, etc. With your boss and others sitting within eye line of your (open) work space, it would be increasingly difficult to slack off or lose focus.
The close quarters of this type of environment, would naturally lead to more social interaction among the employees. Talking, joking, working, quickly trading ideas or questions. This would build relationships faster, and perhaps even stronger, because there is a common focal point that every level of employee is a part of, thus binding everyone together. This connection can build into almost a family like connection, kind of like a "in the trenches together" type mentality. It can be invasive, but that can be addressed and dealt with across the table, in almost literal "lateral management" style.
Each company has multiple people, in different fields that need to work together. With big offices, people need to run around finding others and setting up meetings. Calling, emailing, messaging, all checking in to see if they can meet to work things out. If everyone you need to work together with is at one big table, you don't need to send anything or run anywhere. Just check with them sitting right next to you and get things done faster.
Now, this style certainly is not for everyone, or every company. But it's main focus should be. That of creating bonds and strong working relationships first, rather a false sense of security and importance that comes from more office real estate and materials.