I can think of one good use for body moulding...if you live in an urban area and park in parking lots on a regular basis, when the jerk who parked too close next to you slams his door into the side of your truck, his door's hitting/damaging your body moulding and NOT your paint.All that stuff does for looks if add some brown stains down the side of your truck after the 1st winter
Trust me on that one
Also, if it's strategically placed, I imagine that the moulding can hide the tape lines