Risk Management to include original risk and current risk profile
You currently provide the appropriate attributes the risk as it currently stands. We should be able to keep the original risk probability, impact & score as this is valuable information knowing that implementing mitigation strategies will reduce the risk from the original risk profile to the current risk provide. The original risk does not need to be graphed, but at have 3 fields to retain this information.
Laszlo Kosa commented
So if I understand well, you're pointing out the fact that risk factors (probability and impact) can change, especially with mitigation.
Your need would be to get this "original probability" and "original impact" easily for the risk. (It is already available if you browse the History - but it is not easy to dig out for sure.)