The answer is simple, Volkswagen has never in it's history built a new car that wasn't better than the one before (their cars are constantly improved), the cars were always improved and one of the selling points of the Super was it's better handling (you can read and see that statement in VW's 70's adverts).

Comparing a Standard to a Super is like (suspension wise) comparing a Porsche 356 to a 911... the design just kept getting better and yielding better results on the road/track.