The standard for the German Shepherd Dog, while annoyingly vague in many respects, has not changed appreciably over the years. Unfortunately, the same cannot be said of the breed. From the 1940's, when most dogs in most countries looked pretty much the same, we now have West German show, West German working, East German, Czechoslovakian, English Alsation, American show and probably others yet in the making. Partly this is due to a natural, genetic diversification of families, and is probably a good thing.
Related dogs tend to look alike.
Partly it's due to legitimate differences in breeders' preferences. Working line breeders, for instance, will tend to put less emphasis on movement than on drive. But in many cases it's just ignorance of what correct conformation is all about. The short legs and long bodies of the Alsation were simply not efficient. Neither are the extreme rear angulation and sloping toplines of American show dogs, nor the roached backlines of West German show dogs.