Every case is different. In this specific case, the female victim, at barely 13 yrs old, saw her parents get blown away by a shotgun, by her attacker. They died so he could take her and hold her hostage. That sets up a very horrid emotional situation for this young girl.
I am not saying she is too weak to nail her attacker in court. I am simply questioning the necessity, given the fact that he will be on trial for double felony murder and child abduction. He will likely get 100 years or more, no chance of parole. So what id the point? Why put a fragile 13 yr old out in the public, high profile stage and have her discuss her 3 months of torture? I don't see the upside of that, JMO.