Continuity mistake: When Kaneda shoots Tetsuo with his laser gun, it makes a hole on his shirt. In the next scenes, the hole is gone.
Continuity mistake: When Kaneda and the others are being questioned by the police, you can see a colored strip on the interrogator's uniform lose it's color. This happens in the special edition too.
Continuity mistake: On the bridge, in the next shot after the tank misfires, there is a red car on one of the bridge sections to the right. As the midsection begins to rise up it vanishes. Since the car right behind it does not move, as the section has not yet begin to fall, it's safe to assume this was a mistake.
Continuity mistake: In the scene where Tetsuo mutates and kills Kaori, as the Colonel starts to walk away his mustache is skin tone, not colored.
Answer: In effect, it should symbolize (just as the other psionics say) that humanity is not yet ready to control such power; we are mentally not 'mature' enough. And since we are mere 'children', we tend to play with that power without any real sense of responsibility, and before we know it, it goes out of control. In effect, it mirrors the lack of sense that we demonstrate in our real world, with our technical and political power.