The Headlight washers/wipers are very effective in parts of the world where we have salt brine on the roads during the winter. No matter how good your headlights are, once they're coated with that stuff (takes about 2 minutes) the headlights are virtually useless. Under these conditions those funny little wipers are a major safety asset!
...Unless you figure a Mercedes shouldn't be driven when there's road salt or mud around. Personally, the thing I find most admirable about the MB (at least the older ones) is their safety and durability under less-than-ideal road conditions.