Its resiliency, thick padding will void your carpet warrantee. Look at it like this, carpet pads are like springs the denser it is the harder it is to push down, the more resilient it is gives it the ability to spring back when being pushed down. The best thing for you is a densified urethane padding like Carpenters crown cushion. 7/16 or 1/2 inch padding will not make your furiture unstable.