The RAF requirement is covered well by the excellent book by ‘Jeff’ Jefford - Observers and Navigators (and other non-Pilot Aircrew in the RFC, RNAS and RAF). The real reason was to attract the right calibre of individual to fly, command and with the potential to reach into the upper echelons of the RAF. Simple as that. Society was changing post WW2 and the ‘lure’ of being a SNCO was not big enough to attract the right folks. They even developed a kind of ‘sub officer cadre’ with the 1946 Aircrew Scheme, with their own messes and rank badges (Aircrew Cadet, Aircrew 3rd Class, 2nd Class, 1st Class and Master Aircrew) - this was to try and attract again without needing to put through Officer training. Winston Churchill had always insisted on using SNCO rank to attract the right calibre of folks to become Aircrew, however, it was a temporary measure and by 1946 the new scheme came in. It lasted until 1950 as it was highly unpopular too and they reverted to Aircrew Cadet, Aircrew Sgt, Aircrew FS and Master Aircrew - they remain to this day for WSOps in non-Pilot roles.
The odd thing is that if you pay SNCO Pilots the same rates of flying pay (or RRP(F) these days), like the British Army do, then they end up MORE expensive than Officer Pilots! So what is the point? Officer Pilots only become more expensive as senior Flt Lts and when you take the early expense of SNCO Pilots, it evens out about 16-20 years in. Only really when an officer promotes to Sqn Ldr do they really pull away from the SNCO Aircrew pay.
That’s an abridged version of Jeff’s book, but I recommend it as a great read and an absolute mine of excellent, well researched information and proper facts: