Michael Philpott got a life sentence, of which he will serve a minimum of 15 years. That may seem unduly lenient, but the fact is that a parole board will be extremely unlikely to release him. Mrs Justice Thirwall referenced that in her sentencing remarks.
You can read them here, if interested. They give a clearer perspective on the trial than some of the media coverage: http://t.co/HsEWCF8lvh
The result is that he got the same sentence as he would have done if found guilty of murder. He could have been charged with murder, because as the law stands intent is not necessary if you were reckless to an act of which death was a "virtual certainty". I suspect that the prosecution didn't attempt that because there was some evidence that some attempt was made to control the fire, showing an insufficient degree of recklessness.
Well, I don't think there is a suggestion that the fire was meant to spread to where the children were. We know that attempted murder is not beyond him, but I think it was idiocy that killed those children.
The great genocides of history are the things we know about. It's difficult to assess whether this is an era of particular inter-personal cruelty or callousness. My feeling is that we live in an unusually benevolent time, where sordid crime is simply more likely to be discovered. Modern states are far less harsh in the treatment of their people than many of their historical forebears (look up John of Leiden or Guy Fawkes), and you sense that is a reflection of the general tolerance or enthusiasm for bloodshed of the given era.