Judge Hubble said Ms Insley's submission was "persuasive" and he agreed to the discharge.
He said he was mindful of occasions when New Zealand representative rugby players had been refused entry to Canada because of similar convictions.
Mr Hampton said he was "very surprised" when he heard about the case. "I would say it's quite exceptional for a discharge without conviction to be granted in these circumstances," he told the Herald.
Asked if he thought the woman had received special treatment because of her sporting status, Mr Hampton replied: "It sounds a little like it, and one wonders whether that should be the case.
"You think of various high-profile people who have been charged with drink-driving - from actors like Robyn Malcolm to lawyers like Colin Carruthers - and they don't ask for suppression of name and they don't see it as a hindrance for them going overseas, because I am sure it's not."
Malcolm and Carruthers - also a QC - both pleaded guilty to drink-driving charges last year and were fined and disqualified for six months.
Mr Hampton said he could not understand why the discharge or name suppression were granted.
"In New Zealand, sports people are exemplars for the rest of the community and young people hold them in a high regard. If they, like all of us, have flaws, shouldn't the young people who hold them up as examples know about their flaws and be aware of them? It's not a good message to send, quite frankly.
"I think the police would be justified in feeling somewhat upset about this ... Here's this person doing it and the court in effect condoning it. I think that sends the wrong message."
Students Against Drink Driving chief Anna Braidwood was disappointed by Judge Hubble's decision.
"We hope that it does not inadvertently send the wrong message out to our young people - that in some circumstances, or for some people, drink-driving can be excused.
"When someone chooses to drive drunk they not only endanger themselves but they endanger the lives of other, innocent road users ...
"We struggle to believe that there have been no consequences for the person involved in this case, regardless of who they are or what they do."
The Sensible Sentencing Trust also criticised the judge's decision.
"What's next?" said spokeswoman Ruth Money. "Automatic suppression for everyone who chooses to break the law? Crime is a choice; commit it and be named. That is open justice."