sargs, I think you are partially right. However the aircrew in WW2 were prone to capture and it is possible that they were made SNCOs as they could expect better treatment than airmen.
Then more recently we have example of other rank inflation with numbered sqns commanded by wg cdrs, flts by sqn ldrs. Similarly VC10 captains used to be made up to sqn ldr. And an all officer pilot/nav cadre originally because of the responsibility attached to nuclear release.
One reason has been to give them the appropriate pay for the job when a sharp payrise in current rank would be divisive in the service an dpolitically unacceptable outside.
Less obvious is that you might accept being b***** around mor eif the pay is better.
As for policy, there will have been carefully argued papers that justify this rank inflation and not one would mention any of the reasons given.
The last SNCO aircrew in pilot/nav branches were phased out around 1961 with master pilots only disappearing with the Anson stn flts. Those that were not commissioned often became operations officers, CSRO or sim instructors or airmanship instructors.