: If anything, I think that 343i has completely undermined Halsey's moral
: quandary by introducing the Spartan IVs. Not only are they a stupid and
: needless addition to the Haloverse, but somehow they're able to get the
: same level of augmentation without the augmentation being performed during
: puberty.

: One of the biggest reasons for using children in the first place was that
: they were able to survive the augmentation process. The change removes the
: "Necessary" from "Necessary evil".

The Twos had a fairly successful augmentation success rate, and that was only perfected for the subsequent companies of Threes. Concurrent to Gamma augmentations, perhaps, tests conducted by ONI may have proven that the protocols have matured to allow for adult augmentation without the complications seen with Orion.

In a strict warfighting sense, with no concern given towards who the enemy is, the Fours are an excellent investment. Instead of maturing a six-year old until age 14 or 15 in the rigors of combat, while stripping them of much of their individuality and potential experience, they get supersoldiers with immense background. They're picked from a pool of billions, all volunteers, all successfully augmented with the same capabilities as their predecessors. However, their advantage lies in 17-20 years of maturity, years on the frontlines as a regular troop, and experience in the field as special operations troops

I would imagine that the administrative, dental, housing, medical, nutritional, and psychological costs for a child would far exceed what can be given to adults. Already there you're saving tens of millions over a 7-8 year training course. With the Fours, all of that training is provided by the "general" special operations forces. When they come to the program, they're already highly competent warriors. The only training they need is acclimation to the augments and armor. Since they can augment so many Spartans and quickly transfer them back to the field, they'll need plenty of gear and mass production is kicked up lowering costs.

As great as the twos or threes of Blue Team are, there's no reason not to have their capabilities at a battalion-sized unit or larger cheaper, faster, and just as efficiently.