Media commentator Gavin Ellis said he believed Kiwis felt a collective responsibility to find Millane and make her safe and contributed to the emotional appeal of the story.
"It's not a unique crime, but those other factors are what pushed it above the norm and gave it emotional context."
Posts on social media about Grace's tragic ending shows it keeps playing on their minds and strangers are sending thoughts and condolences to her family via Facebook.
NZME head of social media Tina Moore said her team had been monitoring the comments closely and the public response and outpouring of emotion and grief centred around a feeling of national embarrassment that NZ should be a safe place for tourists.
People were also worrying about how it would taint New Zealand's image on the global stage, her age, and the feeling that it's so close to home and could have been any young girl out in Auckland.
Women in particularly were identifying with the story, she said.
Thomas Cheshire from Sky News UK is one of those who had flown here to cover the story.
He told Newstalk ZB's Larry Williams that people were talking about it all through the UK.
"It's really resonating back home. It's been top story – all through the weekend, it's been high on the agenda."
Cheshire said Brits thought of New Zealand as a very safe place.
"For something like this to happen here, it's even more shocking."
There had been a lot of concern from the families of UK backpackers he had spoken to.
Cheshire believed some people may be more cautious about coming here but did not think it had "fundamentally changed British people's perspective of the country".
Hamilton East MP David Bennett posted on Facebook that Kiwis were "genuinely horrified and ashamed of what has happened to Grace and our thoughts are with her family".
"Such a terrible tragedy for Grace and her family when she was supposed to be having the adventure of a lifetime ... we pay tribute to her and her family as they grieve, and also the police, who have done an extremely professional job and clearly also feel the family's pain ..."
His sentiments have been reiterated by thousands of Kiwis.