I think it has affected so many people for so many reasons of which I will only mention a few:
She was a young women and so many of us are a similar age to Jill so it really "hits home" that it could have been me or a loved one.
She was only several hundred meters from home, she should have been safe.
She didn't appear intoxicated, some people feel that you are more of a target if you are staggering or obviously appear drunk
It happened in a "nice" area
It was busy at the time it happened and on a busy road not a dark alley
As mums it shakes us to our very core that our children could be left without their mum.