Well,... I'm a backcountry skier. I climb mountains and ski back down them... The snow conditions are natural in the BC, so there's no "control work" done by a ski patrol to mitigate potential avalanche danger. People regularly die skiing in the backcountry. One of my best friends died in an avalanche last year....
In BC skiing, we talk about 2 things. The liklihood of a problem based on the science of the snowpack conditions of each day, and the consequences when a problem occurs. We balance our risk factor based on these 2 probabilities, and proceed accordingly.
IMO, The IOM course's consequences are the persistant problem. You can't safely do 160mph right next to brick buildings and rock walls. A miscalculation has a high possibility of deadly consequences. So the problem isn't that a given rider can't negotiate the course at incredible speeds, The problem is that the consequences of a mistake are so costly, that the risks are foolish to take... This is how we balance avalanche risk in the backcountry... The severity of the consequences effect the amount of risk a skier should take, NOT just the liklihood of an avalanche.
IN the case of the IOM, I don't see adding some padding to a brick wall reducing the consequences of hitting that wall at high speed by very much...
Other forms of racing have things like sand traps on corners to slow down vehicles that 'miss' the corner without there being a potentially deadly traumatic force from an impact. NASCAR has soft walls, hans devices, and car crumple zones. There's not much that can mitigate the consequences of a rider crashing into a brick building at over 100mph. IMO, the consequences of a mistake in the Isle of Man race are to high to justify the risk. While I respect the skill of the riders, I also think the consequences of a mistake are too high to take the risks they take.
*As a note to the analogy of my friend, he died on a low probability avalanche day, but he was swept through a grove of trees and killed by blunt force trauma from hitting a tree at speed. The grove of trees being below his route should have been considered as increasing the consequences of the minor avalanche he was caught in irregardless of the fact that the liklihood of an avalanche that day was low.... the consequences were high even though the risk that day was low and that should have effected the amount of risk that he took that day...
I get it. The riders are incredibly talented and can go at terrific speeds. I don't think they should do it on "that course" because there's too many places where the consequences of a crash are increased by impact with immovable objects like rock walls and buildings...
