That’s been the military system the world over for millennia - not really a uniquely British thing is it!
And officers don’t just manage - they lead.
Also - you can be a pilot and an enlisted soldier (Sgt and up) in Britain unlike in the US, so we do not differentiate as much for that role as the US does!
That cuts the career by 4 years, meaning that a larger portion of it is training and a smaller portion is being useful. There is then an incentive to let excessively older people keep flying, meaning a reduction in the physical standards (eyesight, etc.) for the people who fly that $150 million dollar jet. Good eyesight matters more than college gunk like "Art Appreciation" and "Intro to Humanities".
Also I have a feeling the older guys can handle the G's ok, better than a lanky 18 year old who hasn't gotten his man-physique yet.
With the technology we have I think I'd rather have an older, wiser 40 year flying my F-22 than a 22 year old, but maybe I'm wrong, I have no stats for their relative performance.
If the idea is simply use willingness to pay for / put up with university as a proxy to test seriousness and dedication, why not ask prospective aviators to get full-face tattoos? Surely that stunt would prove more dedication than a college degree, and waste less of everybody's time.
The thinking is that officers are personally responsible for the command decisions that they execute. If you are ordered to do something you think is illegal it is your responsibility as an officer to refuse. Enlisted are not expected to be held to this requirement. I understand the realities of things, but this is the theory.
The tie-in with a university degree is that that is supposed to have exposed you to enough other thinking that you are better (not to be confused with "well") prepared to make those sort of decisions.
You could ask this same question about almost any requirement. You just finished saying that prior enlisted are seen as better officers. So why not require all officers to have previously enlisted? (in addition to college or instead of college)
And there are blanket answers to your question that apply to just about anything. souprock pointed out that a college degree takes four years, cutting short their career. And any extra hoops or delays reduce the candidate pool. Remember, the article is discussing a shortage of pilots. The answer might be "because otherwise no one will fly your $150 million jet" or "because otherwise your very few, very perfect pilots will make poor decisions from exhaustion".
Since their incoming pipeline is completely full, if you want to use enlisted pilots you are going to have to pull some officers out of line to replace them with enlisted.
I'm not saying enlisted guys can't do the job, just that this is the way the system works, and this part doesn't seem to be too broken. If you're enlisted and want to do it, the government will pay for your entire college and give you a stipend on top (ROTC, GI Bill), you can even do it part time while you are still enlisted in the military[1], then give you a nice raise to become an officer. Pretty good deal.
The numbers might not always add up for free tuition, but there are a lot of schools in the yellow ribbon program that will cover additional costs for servicemembers[2].
[1] https://www.military.com/education/money-for-school/air-forc... [2] https://www.benefits.va.gov/GIBILL/yellow_ribbon/yrp_list_20...
Because very little you learn in college is relevant to whether you can fly those military jets?