Diseases and sickness are the worst part of open offices. One day one person gets sick. The second day the person to his left also gets sick. The day after, half of the open office is sick. After a week, the entire office is sick. You can almost track the migration of the disease across the room.
Back in France, with private offices, there is a social norm in most companies that in the morning you have to go around and shake hands with everyone.
It's very efficient to propagate diseases. Private offices won't save you :(