perhaps there are issues here that result from the fleet you are from - I suspect that in some parts of the RAF commissioned NCOs were the right chaps for the job etc., and there is genuine puzzlement as a result. In other fleets it has been rather difficult to work out exactly how the selection process worked in a fair number of cases...
You could probably pick 20 people off the street and 10 of them would pass pilot aptitude tests. Not all of them would be suitable to be employed as a pilot.
And therin lies the rub - an opinion shared by many a commissioning board... which is why a number of NCOs I have been crewed with eventually said 'sod this for a game of soldiers' and promptly took the gratuity and any other source of income going, and ended up as airline pilots and captains...
Look at what you wrote, and ask yourself where the logic went - they passed the aptitude tests but aren't suitable for training. (In the role the aptitude test is supposedly suppose to be testing for).
While a significant proportion of officers actually believe they are somehow endowed with a quality that cannot be defined or tested for, the RAF will continue to reject perfectly good candidates.
As for NCO pilots looking at commissioned rates of pay - spec aircrew is an example of how to make staying on a sqn attractive.... and dare it be said, after Sgt Bloggs has got onto his 2nd or 3rd tour perhaps somebody might realise he's a good egg and might be commissioned ready for a Flt Cdr role.... just as happened in WW2.... Was Ginger Lacey correctly appraised originally, do you think?
NCO commissions (in current specialisation) - good idea, but commission the guys who get B or A cats, not the weasels who run the cub scouts etc but who leave the answerphone on when short notice taskings come up.... the RAF's job is projection of airpower, too many people seem to think it's something to do with running clubs.