As the irrational is much more disturbing than the rational, it is not as frightening to see Sin City’s Marv hack up crooked cops with a hatchet, as it is to see Akira’s Tetsuo telekinetically puree unsuspecting government personnel.  Tetsuo’s power is beyond human comprehension, he is confused and erratic, and so his malicious actions cannot be so straightforwardly digested.