Tetra, I like what your saying and agree to a point. But I have to disagree with the phrase "blood vendetta lust" that may some but it's a small minority. My thing is to protect the public, and yes it is a great deterrent. It certainly will deter that person from killing again. try to tell me it won't.
The problem is, it's used a tad recklessly. What I mean is it should not be an option in a case based a circumstantial evidence, or even eyewitness accounts, which can be mis-leading. If you have a guy, that knows the penalty, on a security camera taking a life during a robbery, why should it not be an option? I believe in personal responsibility, the person doing the crime very well knows the consequence his action may bring. It is his choice to act out the crime and face that penalty. How is that different from your "suicide" scenario?