Because this will totally stop and deter anyone and everyone from committing any future massacres. (link) And we can keep on selling, playing with, and firing off our Freedom Sticks.
P.S. Here's a handy quote from our friends over at deathpenaltyinfo.org (link):
For 2011, the average Murder Rate of Death Penalty States was 4.7, while the average Murder Rate of States without the Death Penalty was 3.1
For 2010, the average Murder Rate of Death Penalty States was 4.6, while the average Murder Rate of States without the Death Penalty was 2.9
For 2009, the average Murder Rate of Death Penalty States was 4.9, while the average Murder Rate of States without the Death Penalty was 2.8
For 2008, the average Murder Rate of Death Penalty States was 5.2, while the average Murder Rate of States without the Death Penalty was 3.3
Okay, so states with the death penalty have consistently and substantially higher murder rates -- what does that prove? Just imagine how bad it would be if they didn't have the death penalty!
BTW, did anybody besides me notice that, in a death penalty state, the killer of 48 women received a life sentence?