Primarily because this "coward way out" leads to large numbers of people being unafraid to commit crimes. Would you also refuse to intervene in a rape if you saw it about to happen or in progress? I mean, the cops will catch the rapist eventually. How about a homicide, if you see a few kids stomping a homeless Tuba player to death, are you going to just walk on by? You pay taxes for this kind of thing don't you? The homeless guy can be replaced, your life and limb less so. The cops will catch the murdering youths eventually (RIP Ed, Seattle remembers you fondly).
Maybe you'd also sit placidly on a plane that was being taken over by a few guys with box cutters. I mean, the coward way out is more often than not the smart one, right? Let them have the plane, the airline has insurance and can buy a new one anytime.
Your victim mentality is not helpful to you, or society. You want crime to skyrocket? Play the victim, you seem to have the mindset down. You want crime rates to decrease? Refuse to be a victim. If I go down, I go down fighting. If I see someone being beaten, abused, robbed, raped, I will not stand idly by or walk on past, I will intervene on their behalf. I will not be a victim, and I will not stand idly by out of selfishness while others are victimized.