of course there is a need for cadets.
of course there is a need for GA
of course there is a need for Air Force
why?
a) so it can keep those people who like whinging about a particular group happy (gives them something to post about on pprune)
b) so it keeps a balance in the airline - so that there is no one group telling the other how much better they are
c) it gives the airline the choice of 3 groups to pick and choose from.
Just like a particular cadet may not cut the grade for the airline, the same applies for GA and Air Force. Just because you think you are suitably qualified doesnt mean the airline does! Why would an employer of any industry cut its options down, just because a group of people think they deserve a job!