Why does Shotokai not create aggressive people? This could be due to the fact that the training objectives are never external (for example: "to win" or "beat" the opponent), rather they are internal: to search for self-excellence, to conquer and surmount your weaknesses, become a better human being, all other things can be judged secondary and even superficial if this is taken into consideration.
Aggressiveness is born out of power acquired easily, without sacrifices, these elements united with a weak mind and a weak morality, education and ethical background, are one of the possible sources of aggression and violence. This could be the case of a person that buys a weapon, he suddenly has the power to take a life, in a second he is "strong" and "powerful", without any sacrifices, no discipline, thus he abuses his "instantaneous power", he is aggressive, abusive and inhuman.
On the other hand, after 5 or 10 years of traditional Karate-do training, you have the ability of maiming or even killing an individual with your bare hands or feet, but in those years of intensive training your mind has changed, you are disciplined, you have learnt about yourself and other people, the value of life, the beauty of life, you now control your impulses and have overcome your weaknesses, you have obtained a very strong discipline mind. Even though you may have the power you do not use it, actually you shun violence and go great lengths to avoid conflicts and dangerous situations that could expose you to violence, you conceal your knowledge and never, never ever abuse of your capabilities. This is power (technique) with discipline (disciplined mind).