One more reason I can think of for wide tires in everyday driving is to
avoid loss of control on small slippery patches. For a high pressure tire
with a small footprint, the patch might be the same size as the tire.
Hitting the slippery spot may momentarily cause you to slip. Once you
start slipping, you switch to the lower coefficient of kinetic friction so
even once you leave the slippery patch, it may not be possible to easily
recover. A low pressure tite with a bigger footprint will have more
"choices" for spots to maintain traction.
The same would apply going over a medium-sized rock. The high pressure
tire will lift as a whole and loose contact with the road. The low
pressure tire will conform more to the rock, allowing other parts of the
tire to stay in contact with the road.