Have y'all ever seen somebody tow a heavy load with a lifted truck? It can be done, but lifting a truck seriously compromises stability. The center of gravity is raised, and in a lot of cases the suspension is softened and the steering geometry is thrown off. The big balloon tires flex a lot and usually have a low weight capacity, and their increased diameter works against both gear reduction and braking power. It's all a perfect recipe for a squirrely ride.
Now I can see how a lowered truck could tow just fine if it's done right, though I don't really see the point. In 99% of cases, if the truck is being used as a truck, the stock setup works best. Plus it's a lot easier and cheaper to just leave it the way it is.
1997 Oldsmobile Cutlass Supreme SL. 3100 v-6. Auto. 4-door. Green.
2004 Chevrolet Silverado. 5.3 v-8. Auto. 4wd. Long bed. White.