I didn't know they were supposed to be aggressive at all. I knew about aloof, but not aggressive.
SV
The German Shepherd Dog must be well-balanced (with strong nerves) in terms of character, self-assured, absolutely natural and (except for a stimulated situation) good-natured as well as attentive and willing to please. He must possess instinctive behaviour, resilience and self-assurance in order to be suitable as a companion, guard, protection, service and herding dog.
AKC
The breed has a distinct personality marked by direct and fearless, but not hostile, expression, self-confidence and a certain aloofness that does not lend itself to immediate and indiscriminate friendships. The dog must be approachable, quietly standing its ground and showing confidence and willingness to meet overtures without itself making them. It is poised, but when the occasion demands, eager and alert; both fit and willing to serve in its capacity as companion, watchdog, blind leader, herding dog, or guardian, whichever the circumstances may demand. The dog must not be timid, shrinking behind its master or handler; it should not be nervous, looking about or upward with anxious expression or showing nervous reactions, such as tucking of tail, to strange sounds or sights. Lack of confidence under any surroundings is not typical of good character. Any of the above deficiencies in character which indicate shyness must be penalized as very serious faults and any dog exhibiting pronounced indications of these must be excused from the ring. It must be possible for the judge to observe the teeth and to determine that both testicles are descended. Any dog that attempts to bite the judge must be disqualified. The ideal dog is a working animal with an incorruptible character combined with body and gait suitable for the arduous work that constitutes its primary purpose.
I bolded the part that pretty much sums it up, but I see nothing that calls for aggression