I think vehelpfulguy has perfectly isolated the issues here.
It is far to easy to throw up our hands in horror at the 'wicked' parents, but no parent can make a concious decision to maltreat their children to this dgree - unless there is an element of mental disfunction at work.
Sadly, there are large numbers of people who have little or no direct control over their lives. Things 'happen' to them, and they go along with situations without thought or action.
It is so tragic that these people are allowed to live like this, or in this poor little mite's case, to die like this.
It is far too easy to point eh finger at Socail Services, when anyone who knows anything about their situation knows that they are under-resourced in both personel and budgets.
Still, you can't fight foreign wars on two fronts and have a decent society can you? We just need to adjust our priorities and this kind of tragedy could disappear overnight.
But it won't happen.
That is the real tragedy - not just that this has happened, but that it has happened before, and it will happen again.