It strikes me that the UK rules on this are the most sensible around - and don't seem to be that complex! What they appear to be doing is recognising that there is one form of VFR flight that carries with it a significant risk that you may be forced into cloud and telling us that we may not take that risk unless we undertake an additional 15 hours of instrument flight training. Elsewhere they do not have such a rating so would have to require a full IR to allow VFR on/over the top. Whatever one thinks about the IMC rating and what skills it equips you with (there's another argument we could all have again!
), those 15 hours are probably enough to save the life of a non-IR PPL who gets caught out above an unbroken deck of cloud!