I am no expert here but it's probably because it was not premeditated or he didn't mean to kill her.

Judging by his texts to his husband, he did not try to hide the fact he was struggling to cope but he did try to hide the facts in court.

Can't recall what cases exactly but there have been many where there is premeditation and lesser sentences passed.

I don't feel anything more than vitriol for the bloke and 'scumbag' pretty much describes him but he will have to live with this for the rest of his days.

I also disagree with some posters in that the system must take some blame for the death of this poor child.