Answer:
The answer is it had airfields that the USA needed.
Explanation:
First of all, AA missiles weren't even a thing then.
We devastated the Japanese navy at Midway prior to invading Iwo Jima.
China had resources that the IJA needed. Not Iwo Jima.
Iwo Jima was one of the staging areas for the USA to send bombers to quite literally, drop the sun on Japan... Twice...
