Allow me to educate you.
Risk is defined as Likelyhood of occurrence vs severity of injury.
It is possible that something is highly unlikely to occur, but the extent of injury is so great (fatal etc) that the "risk" is considered above something that may occur more frequently with insignificant consequences.
Basically a balance of probabilities, as it's called in health and safety.
Now. Saying "when is the last time x y z happened" is a dangerous road to go down. There will be a reoccurring eventually, it's just a case of when. This is why procedures are put in place and maintained. Often the cause of such reoccurrences is due to human error or rule based violations, if you want the technical term, where someone has thought "meh, this filter doesn't need to go on the fuel hose.. We've never had a fire", so they purposely defea the safe systems to benefit themselves or cut corners.
In my opinion this closed cockpit concept may reduce the risk of driver injury, but as pointed out will cause other issues with straight line speed and emergency access etc. I'm not so sure it's needed.