While skid plates provide crucial protection for your 4×4 first and foremost, they have a couple other nice benefits.
With a smooth, uninterrupted surface underneath your 4WD, you will be able to slide over obstacles with less resistance. This is true in rocky terrain as well as when breaking trail in deep snow.
While adding weight to a vehicle is generally a negative thing, skid plates are located so low on the vehicle that they will actually lower the center of gravity of your 4×4. This improves stability and handling both on and offroad.
The final benefit, though minor, is wind resistance. On a lifted 4WD vehicle, a lot of air ends up traveling underneath the vehicle at highway speeds. This increases drag which can hurt your fuel economy. A smooth uninterrupted skid plate set will reduce that wind resistance.
