The increased scope would improve the quality of the candidates as more people would be eligible.
They might argue that the quality of the candidates is already very high which is why the qualification bar is set where it is, and despite that, only a small percentage of those candidates will be successful. The number of opportunities available under this scheme is fixed and the eligibility numbers are already high enough.
One last thought. Are those people that are leaving higher paid jobs (Doctors were mentioned) contributing more to society as a British Airways pilot vs their current employment?
Possibly, or possibly not, but that isn't really the issue. For the candidate it is an elective choice, and for the company it is an apprenticeship opportunity offered in line with a projected need for specific labour.
You need to keep this in perspective. It is an apprenticeship opportunity for those who might be interested, driven by commercial interests.