I don't think the decision can be summed up a a simple right or wrong one. There were a lot of complexities involved, and Covid has actually changed some of those.

NZ2 / NZ1 increasingly lost passengers from AKL<->LHR O&D route as more and more people switched to ME3 and Asian carriers to get to Europe. This was for a number of reasons - with the LAX transit being one (but I never had a bad experience despite doing the flight many times), and secondly Air NZ still trying to maintain a a price premium to fly NZ metal the whole way. You could fly via Asia for way cheaper or routinely book AKL-LHR via LAX and fly VS/BA/UA on the LAX-LHR route and save significant $$$ as well.

Near the end it wasn't uncommon to find well 50% at most of the pax leaving LHR or AKL flying right through. This was made up for by it being a very popular option for UK and US pax to fly the sector and a lot of celebrities from both countries.

Despite claims by some people that it was making a loss it does not appear that was actually the case. It certainly can't have been a hugely profitable route near the end because the costs for Air NZ were huge - I would simply hate to think how much it cost them to have a crew base in the UK with cabin crew that only ever flew a single sector.

Covid and the war in Ukraine has now changed some aspects of the business case behind that.. There aren't the same number of options to get to Europe via Asia due to airspace closures and popular transit points such as HKG are now a poor option due to the significantly increased flight time to get to Europe. The focus on the US is now showing cracks as parts of the US economy are clearly not ideal either and the demand for travel from the US to NZ isn't great despite the exchange rate and the massive cutback in US capacity by both Air NZ and US carriers shows that.

Now SIN is the hotspot for travel with the UK / Europe with 4 x daily flights from AKL-SIN on both NZ and SQ as part of the joint venture as well as the CHC-SIN SQ flight.