Justice is for the living on earth, IMO. It is important for us and the victim's loved ones (usually) that there be justice. We also need it, as a society, to deter others from committing heinous acts.
I think the dead, if they were innocent or good while on earth, are beyond feelings of recrimination or revenge or punishment. Caylee still feels love for the people she loved when she was alive. And whether casey is punished or not is likely completely beyond what's important to her at this point.
But I do think that the dead value the truth. They want the world to know what happened to them. They want their loved ones to know the truth. Caylee cannot comprehend why her mother murdered her. And part of having the truth revealed is being able to ask the questions they could not ask when living, "Why did you kill me, Mommy? Why?" And it gives the voiceless dead a voice they otherwise could not have.
Caylee cannot tell us what her mother did to her. She cannot talk about her final moments - of the confusion, the fear, the panic at not being able to breathe, the horror that her "mommy" was not helping her. But a jury verdict can tell us for her. I do think that's important to angels like Caylee whose voices have been prematurely and horrifically silenced.
That was an absolutely beautiful way to put this. Thank you so very much.