if you are on a group ride, the amount of time you may have to wait at a regroup for slower riders isn't really meaningful.
Actually I was just getting ready to say the opposite. If I'm planning a group ride, I need to know the overall average, which includes time stopped.
example: We did a slow no-drop ride on Sunday. Our typical riding speed was about 17. After the ride, my computer said the average speed was only 14. At first I assumed that included rest stops, and I started to use that pace to plan next week's ride. But then I realized my computer is only computing while moving. I'm surprised that our "average while moving" was only 14, I guess we spent a lot of time slowing down for traffic lights every 1/2 mile or so.
Anyway, for planning purposes, since my computer doesn't report "total time" or "overall average speed", I need to remember to keep track of our average moving speed, the distance, AND the amount of time at regroups and rest stops.