If capital punishment is not done with spite or malice then why do they consult the victim's family when deciding whether or not to seek it?
Because given the clusterf*** that is capital punishment in the United States, trying to obtain a death sentence without the blessing of the victim's family is pretty tough. Even with it, it's not easy. (Not that getting it should be.)
As I've said before, while I support capital punishment in the abstract, I don't support the system we have in place in this country. However, I also don't think trying to make it a worse system as the yahoos making it more difficult to conduct lethal injections are trying to do is going to erode support for capital punishment.
And most importantly, a victim (or their surviving family in a homicide case), should ALWAYS be at least consulted for input on sentencing options in a case. Note I emphasize "consulted" for "input", not given veto power or final authority on resolution.
FWIW, in the murder trial I had several weeks ago I met or spoke with the Victim's family nearly half a dozen times in the several months the case was pending, plus every day throughout the two week trial.