I was pilloried some years ago when I mentioned airman tendencies in officer candidates. I think this thread epitomizes that. While some NCA have all the attributes for commissioned service (I know one AEOp who made Air Cdre) there are many that do not but may think they do. Remember many were rejected at OASC and offered NCA.
Staff work was mentioned, your lowliest JO is exposed to different and varied staff work by means of jobs pushed their way. Responsibilities are different and officers often have to act on their own when NCA, in the broader sphere do not.
I served with many superb NCA some of whom could have been commissioned and some, despite their own assessment never, Wenselydale may know of whom I am thinking.
Mention of officer and NCA in WW2 is a red herring as societal norms played a large part in initial appointments with commissioning quickly following upon performance.