When a rule or regulation is written as a result of an accident, it is often a question of a*se-covering instead of protecting since the regulatory body must be seen to do something rather than accept that those particular holes in the swiss cheese are ever likely to line up again.
It is the same mentality that allowed the unrestricted growth of Health and Safety legislation - it started out as a good idea to protect workers in the workplace and has ended up as an unwieldy series of rules and regs that hamstring the emergency services on a daily basis and make most normal people's lives far more difficult than they need to be.
Life is not zero-risk and never will be (thank God) and some of the jobs that need to be undertaken in aviation will always involve some element of risk.
If the CAA were really serious about safety, they would have mandated post-graduate training for PPLs many years ago. Without further training, a pilot only has his experience to go on and, if that experience is based on luck rather than skill (getting away with flying in marginal weather for example)then it should come as no surprise that eventually a few get caught out.
Rules don't make things safer - good training makes things safer.