Why serve pro bono in death penalty cases?

Why are so many lawyers willing to provide pro bono legal representation to death row inmates and defendants charged with capital crimes? Don't some people deserve to die? Deserve it or not, we're all gonna die. It's just a question of how and when. For most people, the inevitability of death is psychologically acceptable due to the fortuity of the "how and when." Executions provide the antithesis of this psychologically appeasing fortuity. For many pro bono lawyers, there is a palpable irony to the death eligibility of a crime being based upon the level of premeditation involved. Indeed, our own legal process in death penalty cases rightly embodies a systematic, methodical premeditation in its phases and stages that far exceeds any possible level of premeditation involved in the underlying crime. Premeditated killing gives many good people "the willies," no matter what the justification. This is particularly true when the level of premeditation bursts through the top of the thermometer. Yes, there is also a great concern among pro bono death penalty lawyers about executing either innocent or, even if not innocent, "less than deserving" defendants. No bureaucracy gets it right every time, especially not ours when it comes to law enforcement and prosecution. We know this with virtual certainty, don't we? So, what percentage of the time does our law enforcement bureaucracy, well intentioned as it is, make a mistake? Less than 1%? More? What is an acceptable percentage level of mistakes in the death penalty area of law enforcement? These are some of the reasons why so many lawyers serve pro bono on death penalty cases. There are others, but I find these compelling enough.