On the manual's towing section it says

"Do not exceed a towing speed of 45 mph/70 km/h and a towing distance of 90 miles/150 km, otherwise the automatic transmission may be damaged"

Obviously this wouldn't apply when using a conventional flatbed tow truck, but it got me asking why the automatic transmission may be damaged when pulled while in Neutral.
My guess was the transmission cannot be cooled down properly when driven with the ignition off and in neutral for too long.

Anyone know the answer?