There are fewer things in life nicer than those first few shots with a brand new sheet of rubber right out of the package. This is especially true with a grippy sheet of inverted sponge, with its surface practically grabbing the ball and throwing it back at the opponent with topspin or whatever type of spin you choose.
If you take proper care of the inverted surface, your rubber can do this for a long time. However, many players do not clean their rubber, and so dust and grime collects on the surface, leading to a non-grippy, often inconsistent hitting surface. The ball starts to slide on the surface, and you lose spin and consistency.