Its not a height thing you are supposed to use the running boards to decrease wear on the sides of your leather seats. If you do not step out of the car you continually slide off the side of your seat and if you even look after a few months the side of the seat will be much more worn than other parts of your seat.

And brian5 that is not a running board, MB has an optional running board. If thats more of what you wanted you should have opted out of the running board option