I believe they are for the factory to suspend the car down the line, and jacking points in one, but must admit they aint the strongest thou.
Also if you have the sporting skirts on (well at least on my old mk1) theirs two arrows either side of the skirts and the ones at the fronts seem to be pointing to that support and thats the only thing i can think that their for, to tell u where the point is.
Any one else noticed that?