Didn't aprreciate that you were a medic, QDMQDMQDM!
I think the rationale behined the NPPL medical sign-off is pretty robust myself. Decades of gliding experience showed that pilot imparement or incapicitation simply was not a significant factor in accidents. (Glider pilots are signed off by their GPs.) In several of the tiny number of cases where pilots had actually conked out, the individual concerned was a PPL holder with a current medical!
As private pilots, we are not routinely whizzing up into the stratosphere or hurling ourselves into the sort of inner-ear challenge that is military fighter flying. Nor should we expect to be rejected by the system because we are not perfect physical specimens. Why should we Sunday flyers be burdened with medical requirements that were first formulated for the RAF, especially when they appear to have a negligable impact on flight safety?
One of my friends is currently engaged in one of those hugely expensive one-CAA-medic-after-another cardiac referral sagas. £1,000-odd later, he will get his Class 2, fly for years and die in bed. He tells me that he can afford it, but just think how many flying hours this saga could have cost him, and certainly would cost most of us. Here is the real crux of the thing: it is practice that truly makes the safe pilot!