Experience shows they're just the opposite.
The point is not to have much of the environment hidden from sight. The point is to prevent the 'All I see is open road' feeling. On a slightly too simple note, the point is to make you feel like you need to be more careful without actually adding a lot of risk.
One might say the current road design makes roads feel so safe that the actual safety benefits get canceled out by changed behaviour.
This sounds like a recipe to increase accidents, just saying.