This has happened before - whenever measles vaccination figures drop, ultimately there is an outbreak and sadly some children are left disabled or, worse, dead.
What I was taught is:
Measles is v highly infectious. If you have no immunity and spend as little as half an hour in the same room as someone harbouring measles (no body contact necessary), there's a 98% chance of you catching measles.
To prevent outbreaks 90% of the population needs to be vaccinated. The figure is a lot lower than this in some parts of the country, so outbreaks will occur.
It seems to be a sad truth that sometimes the only way to persuade some people to vaccinate is for their to be widely reported deaths.
We don't know the story behind this family. Whatever it is, the parents will now be suffering more than most of us would ever want to imagine, and I don't think anyone should be throwing stones.