Great question, and one rarely touched on...
16" and larger wheels were introduced to address handling performance, load capacity and the fitment of larger calipers and rotors. All of this has to do with the faster road speeds in modern times. A 16 (or 18" for that matter) wheel will deflect less under cornering loads, allowing the vehicle to respond faster to steering input and reduce the likelihood of understeer due to the change in camber caused by sidewall deflection. Lower profile tires also generate less heat (as a result of carcass flex), which allows for great top speed ratings.
I prefer a 16" wheel for expedition work, as there is a greater selection of load d and e rated tires, and most are specified in the ETRTO metric sizing, which favors a narrower aspect ratio.
But, as with everything, there is a compromise. A 16" wheel has a greater chance of damage on the trail, and there is a shorter tire sidewall, which is important for flexibility when aired down.