Internationally, New Zealand has a high prevalence of asthma, with one in seven children (13 percent) aged 2–14 years (110,000 children) and one in eight adults (12 percent, 452,000 adults) and that is reporting taking current asthma medication. (whilst not the highest in the world it would have been taken into consideration when making the decisions). Add to this number around 200,000 Diabetics.

Asthma and diabetes being on the high-risk list for COVID-19. Now add in your elderly with past medical issues and any other New Zealander with any medical problems... it is a huge chunk of the small population at high risk. Also, New Zealand's first case of COVID happened in February, and the lockdown happened in March which is the beginning of Autumn. Currently, August middle of winter New Zealand is in the middle of its Flu season. So extra precaution needs to be there as well.

New Zealand only has around 358 ICU beds and only about 334 ventilators spread around the country in its various hospitals. The whole idea of any lockdown is to not overwhelm the health system so that there are always ICU beds and Ventilators available for COVID-19 victims and other emergency victims. 

As Dr Arindam Basu warned that if New Zealand adopted an approach similar to Sweden, and even a conservative 10 percent of the population caught COVID-19 that would still be 500,000 people which could overwhelm hospitals.  And that's when more deaths would happen from COVID-19 and other emergencies as the health system is overwhelmed.

Also, remember Auckland is not in full lockdown at the highest alert level before lockdown Alert Level 3 and the rest of the country is only at Alert Level 2) The whole plan from the beginning was isolate any outbreak before it gets out of hand in any way which would result in another countrywide lockdown. Having small outbreaks and controlling them as fast as possible means the health system can keep up.

Economically speaking at Alert level 4 (full lockdown) it was estimated 50% of workers were at home, alert level 3 around 20%, alert level 2 6-10% and Alert Level 1 was all business can operate. We are still aware and taking various precautions at the border etc. But mistakes happen, human error happens and we will most likely have a few more outbreaks here and there till a vaccine is available.

Throughout the full lockdown, import and exports still happened, while many local businesses struggled many found new ways of doing things and while yes, some went under, many found it was not as bad as they thought it would be and have had to pay back the wage subsidies.  But no matter which way you do it every country will have a downturn.

As for the myth of it being no worse than a bad flu year and fewer deaths than influenza. The World Health Organisation says COVID spreads faster, and 
https://www.who.int/emergencies/diseases/novel-coronavirus-2019/question-and-answers-hub/q-a-detail/q-a-similarities-and-differences-covid-19-and-influenza

So please take this into consideration when you start any criticism.