I miss the AIM days when you’d hear the “door opening” sound when someone signed on. It was totally normal to immediately ping someone then because signing onto AIM was asking to be pinged. And that sound made your heart skip a beat because it might be the girl you like and she might even IM you first :o
I find active/non-active presence helpful so I know whether or not to expect a reply soon.
Plus, I never need to wonder if it's safe to send a message to a coworker for their timezone "George is in Germany, am I going to wake him up if I send me a message now?" I can rely on him setting notifications appropriately.
Privacy and concentration are selfish interests? Why not have a 9-5 webcam of yourself feeding into my surveillance dashboard? This way I can see my team hard at work as I would in an open office. They'll love that.
The prior in-person work setup is not the ideal nor the standard. I don't need or expect others to pay attention to what I'm saying right when I'm saying it unless there's real urgency. We're all IP-enabled meat functions now; there's no going back.