What tasks have the frigates done that they were not able to complete and why/how are they clapped out? You could ditch any role in the military presumably then if you dont actually do it, which in all honesty I have not seen any modern warship conduct any modern combat in literally a lifetime ie no warship vs warship be it destroyer, frigate, sub etc actually coming up against another, at sea, in battle. Sure alot of escorting, some missile strikes, the odd naval bombardment but no actual use of all this offensive technical firepower against other similar offensive firepower (what they were presumably designed for..), and most definitely not 4, 6 or 8 of them as that would actually be an epic undertaking and quite a shift in the strategic situation, anywhere, by anyone. TBH for us what have 2 ANZAC frigates done that 4, 6, or 8 would have done any different bar a WWIII type scenario for NZ and some great sea battle of old protecting the realm and quashing an evil regime? Just not overly sure that no capability at all is a viable better option to a perceived lesser capability based on what? numbers?
Not saying there are not obvious shortcomings with having only 2 frigates available but that is more from an availabilty perspective not usability angle per se ie if I have not used the modern long range weapon that I have then is 2 bigger weapons with bigger mags and an arguably improved targeting system necessarily going to change that whole scenario any or literally just continue the same scenario regardless? To put it into perspective if we were to aqquire any more frigates then I would rather we get a more multi-role option like an absalon type rather than merely just more of the same, to do the same, which is?...
I also tend to agree though, we seem to place alot of military consideration on, of all places, Antarctica! if equipment suits then by all means use it if available but I'm not sure we should be gearing capability towards Antarctica specifically at cost. It should be seen as a bonus of current capability not a requirement of future as like you say, a civilian organisation can take on that burden c/w civilian designed and built equipment.