Eugene Volokh posts an op-ed he wrote arguing against the now-retracted Victims' Rights Amendment and it's generally good, but I think he dances around what I see to be the real issue: the government shouldn't base prosecutions on what's good for crime victims.
Many people (not Prof. Volokh, I'm sure) see the justice system as a civilized way for victims to get revenge. Many others think the purpose of the justice system is to reform criminals and make them into contributing members of society. Both are wrong.
The former view is possibly popular because the perceived need for "closure". That's psychobabble. The government has no business basing punishments on anyone's mental health.
The latter view is popular because there's a certain segment of society that thinks no one is responsible for their actions. When people commit crimes it's society's fault for not educating them sufficiently. I reject this notion, not because there aren't some environmental and genetic factors that contribute to criminality, but because despite those factors we all have a responsibility to exert our free will and prevent ourselves from hurting others.
A third view is that the purpose of the justice system is to make society safer. This is partially true, but not exactly. The purpose of the laws that the justice system enforces may be to make society safer, but the purpose of the justice system itself is purely to enforce the laws. The police officer and the judge should not concern themselves with the effect their enforcement has on society.
The legislature is in charge of crafting laws that fulfill the goals of their electorate, and the voters will probably want their representatives to pass laws that make them safer. The justice system should let the lawmakers do their jobs. Part of the problem is that the lawmakers make so many laws that they can't all be enforced. This situation leaves the justice system with too much discretion as to which criminals they prosecute, and in effect allows the police and prosecutors to act as de facto legislators by ignoring some laws and being strict on others.
The real focus of the justice system should be, as Prof. Volokh says, "figuring out the truth". The victims' rights lobby thinks that trials should be therapeutic for crime victims, but in reality the victim of a crime has no role to play other than, at most, a witness.
If a defendant is convicted he should be sentenced purely for the purpose of punishment. If the punishment brings anyone "closure" or satisfaction as an incidental side-effect, fine. If the punishment makes society safer, that's excellent (and an important indication that the punishment is effective). If the punishment leads to the criminal's reformation and redemption, also excellent. But none of those are the point, and I don't trust the courts to define all those terms. Punishment is easy, all the rest is social engineering.