We should simply be recruiting the right person for the job
Indeed, but if some people who have the right qualities think that the RAF will only let them do "lightweight type jobs" or that the RAF doesn't want them because of their ethnic background, sexuality etc., they won't apply. The RAF is competing with many employers who offer rewarding careers to a diverse range of potential staff; it therefore needs to cast its recruiting net wide and show that it offers opportunities for a wide range of people.