What is Wrong With Stock/Rubber Bushings?
The suspension bushings on most cars are a midrange density rubber compressed between two metal sleeves with many tons of pressure. Despite this compression the rubber still (intentionally) moves under force from the suspension system. This can lead to sloppy handling, numb feedback and so fourth. In some bushings, this movement and cushion is designed in to the bushings for different NVH issues that the manufacturer was trying to solve.