I think that the key issue here is the building regulations are a minimum standard and no reputable organisation would rely solely on building regulation approval as evidence of a safe design. The company I work for used a mantra 'Safe by design', it has been replaced by '100% Safe'. This a very high aim, however it is stated as the primary concern of every designer that it must be 100% safe and will keep the users safe.
CDM requires that all designs must be safe. Any person from the commissioning client down to the final user or owner through designer, design checker, estimator, buyer, anyone who has an input on materials or methods could be considered to be part of the design and should have a keen eye on the safety of the design.
If the cladding (for example) met with the building fire regulations it is not an excuse just to say that it must be OK. It must be shown that the design incorporated it because it was proven to be suitable in the conditions in which it was used and that all precautions have been taken and the scheme risk assessed with that material as cladding.
The UK has some of the most onerous regulation for buildings in the world. We covered progressive collapse of buildings in our codes which may have helped the twin towers not to fall so rapidly in New York. This requirement followed on from the infamous Ronan point gas explosion and other collapses, which also uncovered the use and problems with high alumina cements and system built high rises. Our codes are not the problem, the implementation of them or assessing the potential hazards that could arise may be an issue.