My Pathfinder has mudflaps, has really helped, especially with all the gravel roads I drive on.
Note that with a lot of vehicles, the rear mudflaps may be attached to plastic rather than metal, so the "trapped salt and dirt causing rust" argument does not hold water.
We had our Mystique for 8 1/2 years with mudflaps and the lower part of the body was in very good shape when we got rid of it.