The odometer doesn't rack up miles when the key is off. There's a big difference in coasting down a hill for a mile or two vs. towing a Jeep hundreds or thousands of miles... at least enough difference that Jeep engineering wants to prevent the transmission from spinning when it's not being lubricated. I wouldn't coast down a long steep hill myself, I don't like the feeling I'm not in as much control of the Jeep. Not to mention the brakes have to be used when coasting downhill if there's much steepness to it.