It went because it caused lag. That's why a handful of features went.
Note that some things were taken down due to abuse (chat, mark up) and some simply taken down with the promise of putting them back up (Community online, trashcan).
The green light was laggy, and because of bugs virtually useless.
But the community online feature did not show such errors, and was actually pretty useful. It would be great if we got it back in AG 3.0
If the admins see any value in this feature again, they will probably add it when they launch 3.0