At the end of the day its only the riders that really know if its safe to race and if conditions are not good there is more chance of the faster riders catching up on slower riders that may take a different line as a precaution.
I must agree that the safety measures being put in place these days are good, you only have to take a look at the reduction in fatalities to see this. But you will always have the unexpected, as seen on TV this week, rabbits and hares on the track, and the rumours have it that it may have been a hare that caused the serious crash in sidecar 2 race.