You just endured a long flight, and the last thing you want to do is to stand idly and watch the baggage stroll by. And, we all know stroll is an overstatement. Imagine baggage getting rolled out at 600 metres per hour. Wouldn't that be awesome!
Each tray in the conveyor system has a RFID tag on it, so its exact and precise location can be determined. That said, I sure wouldn't want to retrieve my baggage when its speed is at its peak.
More info here.