Ground speed is useful, because when dividing it into distance to go, the calculation well show how many hours remain for the flight. Altitude is interesting, but not so useful. The only metric that doesn't really have any value at all is outside temperature. Why show this? Am I going to open a window and pop my head out for a breathe of fresh air? No. The only function this serves is as a reminder of the cabin's warmth (even if air is a bit on the cool side).
What other useless information could be included? How about outside air pressure, so we can be reminded that the cabin pressure is moderately comfortable? Instead of altitude, why not provide "distance from outer space" to remind us of just how close we are to entering orbit?
Something that might be more useful is if the map provided information on the destination, like the "current ground temperature" so I know to pull the jacket out of my carry-on luggage.
BTW, I'm ranting this from the airplane. I'm glad wi-fi is now being included on many flights.