I've never considered a 2 wheel drive since we like to camp dirt roads and on the beach. In all the years we have travelled with a truck camper I have only needed to put the truck in 4x4 as the rear tires alone lost traction and slipped a hand full of times. It was sure nice to simply pull a shifter and drive right out.
How many times that we proactively engaged 4x4 for sand, mud, steep terrain etc that we may have been ok in 2wd? Not sure.
If I was buying a truck to only travel on paved roads only I would go with a 2WD. If I were buying a truck to haul a 5th wheel I would go with 2wd as the bed rail height is lower and I wouldn't take a 5th wheel out on 4x4 type roads.