While using cruise, the people behind you will notice how steady of a speed you are going, and might be lulled into not paying as much attention especially if they are using cruise also. if you are not using cruise, you speed will fluctuate, and the distance between you and the car behind you will be varying much more than if both had cruise causing them to be more alert. This is the best argument for needing the brake tap to disengage vs not needing it if you are not using cruise.