First of all, the first article gives little info on the attack itself.
Second, the question was based on that situation but was given as a general question, not just the specific incident.
In regards to the incident specifically, the dog should most definitely be put down, as it most likely was. There is little doubt now that the dog was too dangerous to be a pet, especially in a neighborhood with children. But it isn't because of the breed or the size of the dog but rather because of this incident. If there were other incidents before this one, not just comments on how aggressive/mean the neighbors think the dog was, but actual violent incidents in the past, then the owner should have taken more precautions to ensure the dog did not get loose.
Another thing here would involve whether anyone aggravated the dog, especially people near the house where the child was, before the attack. This is a thing anyone wanting to blame the owner for in any pet attack should keep in mind. You can't say the owner should have kept better control over a dog if someone else is aggravating, hitting, or taunting the dog in ways that a reasonable person could assume might cause a dog to attack.
I have had relatives who had their dog chained on their property, when a couple of neighbor kids went onto the property and were taunting and hitting the dog til the dog bit one of the boys. The dog got put down because of the incident although there is no doubt that he only attacked in defense.
There is a lot of reasoning that goes into determining what happened. There is the reason behind why a particular dog attacked. Was the dog taught to attack people? Was someone trying to aggravate the dog to attack? If so, who? Then there are questions about what the owner did to prevent the dog from hurting anyone and whether the dog had a history of aggressive behavior. Did the dog escape from the property/owner before? How high was the fence in relation to the dog? What was the fence made of? Was the dog secured behind the fence? What was the dog secured with? Had the dog attacked anyone before? If so, was it provoked/unprovoked, on the person's property/in public/on someone else's property? Is there any evidence to suggest that the owner purposely trained the dog to attack people, especially people who would not normally be viewed as a threat, or small animals (I could see a child being mistaken for a small animal if the dog was trained to hunt more than just specific animals).