There was more to the RNZAF's air combat wing (it was more like a squadron and a half) than just defensive counter-air.
Just one of the capablities lost was the ability for the NZSAS to train in the terminal guidance role, previously an important task for them, designating for the A-4K's laser guided bombs. The combat wing also contributed to counter-air training for both the Australian and New Zealand navies. Another important capability was the maritime strike role, prosecuting targets for RNZAF Orions.
A role I'm sure the leaders of the NZ Defence forces would have considered very important was coalition operations with New Zealand's allies in the Asia-Pacific region, particularly Australia, and while the A-4s were getting a bit long in the tooth for real world operations, and some of our alliances had been shaky since the break-up of ANZUS (over US nuclear ship visits) they were better than nothing. Since we're really talking joint exercises (and not a shooting war thank goodness) the A-4s still had a role to play, and the F-16s would have been able to make a genuine operational contribution had it ever been necesary. It was a case of being a responsible international citizen and pulling our weight, something that's important to our allies, and not something we have a great record at - with a per-capita defence budget significantly less than many of our allies.
For mine though, the most important aspect is that even the A-4Ks maintained a level of air combat capability and a cadre of skilled air and ground crew that would have been available for expansion if the strategic situation was ever to deteriorate. That is lost now, probably forever. And the F-16 deal was such a good bargain that even Hawks would have been more expensive I'm sure... so it really was an opportunity lost.
Don't worry though, I downloaded the RNZAF Tigershark from Combat Ace just the other day, and very nice it is too. If hostile planes ever appear in our skies I shall go outside in my backyard and shout 'bang' VERY crossly.
Cheers all
Kiwi