I think this is a fairly deep and important issue and I think you may be taking it too lightly. Good choices vs. entitlements to make choices are absolutely at the root at the whole history of civilization as such. We may easily agree that putting violent criminals into prison is a good choice, but if we all feel entitled to judge 1) who is a violent criminal 2) who belongs to prison, we are quickly back to the system of mutual vendettas that characterizes pre-civilized life. So the idea that beyond the strictest needs of self-defense, we don't claim any entitlement to take any sort of a violent or coercive action but leave it to judges, policemen etc. is that lies at the heart of civilization. (Of course, democracy makes it a bit of a farce, but whatever.)

Same story here. Sacrificing 1 life to save 5 is the right choice, but it is highly dangerous if people feel they are entitled to kill others just because they think they will serve the greater good that way. Every murderer could manufacture an excuse and could try to plead having made a honest mistake at worst. Thus, while it is the right choice, having rules that allow making choices of this kind are not good rules. This is what it boils down to.