If Jackson was successful in that then it's possibly a kind of 'happy accident'. Why? Because Arwen was originally scheduled to turn up and fight at Helm's Deep, and in fact these scenes were filmed but then edited out (you can see a few glimpses of Liv Tyler in some scenes though you'd possibly have to watch the film frame by frame with a microscope
). The contingent of fighting Elves would have come along with her, and there would be no reason to cut out scenes of audience-friendly Elves.
By the way, I think he was successful in getting this point across anyway...