Maybe a big part of the problem is the PPL training establishment which takes a very cautious view.
Pre-PPL, you are flying on the instructor's license (so to speak) and he will not take risks. So a prob30 tempo, no matter how obviously totally wrong, has to be taken as a prob100.
On the self fly hire scene, so many renters are on marginal currency as well as knowledge, that the same applies.
Pilots are also taught to stay VFR (legally they have to) and again this leads to strict interpretations.
If however the UKMO said "OK here is the TAF but you should also look at this and this and this [weather radar, satellite, sferics, etc] " that would be different. But only self-taught IFR pilots discover these other sources - necessarily because the level of weather provision to sub-FL250-capability IFR pilots is pretty crap here in Europe.
If I was running a flying school I would ignore all prob30 stuff for purposes of all dual training/trial lessons and just use the MSLP charts for "will tomorrow be ok" purposes. Ignore cold fronts unless occluded or severely curved *at* the relevant place. Warm fronts will nearly always be crap for VFR...