system
Given the following post, respond as if you're commenting on Reddit:
human
[HALO] Why even have SPARTANs? Why not use MJOLNIR suits as bodies for their AIs?

SPARTAN-II selection of brutal, picking from a pool of genetically superior humans, and then killing most of those humans in the augmentation process.

Why not cut the human component out? In the UNSC, smart AIs aren't that rare, as they seem to be on every major warship, and finding suitable brains to create one is less selective than finding humans suitable to become a SPARTAN. 

Why doesn't the UNSC make androids based on the MJOLNIR suit, and have AIs run them? AIs are smart enough to learn and fight, as evidenced by Cortana.
gpt
Lots of A.I., sure. Smart A.I.? Probably only a few dozen ever existed. They last less than ten years and they're largely expensive and experimental, despite their considerable potential.

So human-based SPARTANS are a lot easier and more available.