I sympathize with people like Linda Casey, who was traumatized by her discovery of her daughter's dead body in the driveway of her North Carolina home, then mortified when the local news played her 911 call in a telecast. But that is still the lesser of two evils.
If such 911 calls were banned out of sensitivity for victims' families, society at large would lose the chance to assess how our local emergency responders handle their life-saving work. For an illustration of how important this is, check out this article, about a family in Pittsburgh that called 911 a dozen times and waited more than 30 hours before paramedics arrived. By that time, Curtis Mitchell was dead.
Emergency response is a public good. And the public should have a way of ensuring that that role is in good hands. It's as simple as that.
But for the Linda Caseys of the world, we just have to hope the media will be a bit more sensitive about airing the 911 tapes.