If you're towing 4 down, the rear tires are more apt to wander than the front, and will wear faster, but aside from that, to NOT unlock the steering would cause undue strain on the front of the vehicle in a turn. that front end NEEDS to turn with the towing vehicle, and if it doesn't, you're looking at some serious tire wear.
Tom - Retired OTR 20 years 2 million mile club - 1984 Diamond Maxi
I love everybody! Even some above ground!