Cats may like to bump into quilts for fun reasons, or because they feel happy and relaxed when doing so. Cats like to play on quilts, probably because the soft surface of the quilt makes them feel comfortable. In addition, quilts can also provide cats with a hiding place to make them feel safe. Another possibility is that cats like to bump into quilts because they can simulate hunting behavior when doing so. Cats are natural hunters. They like to catch and beat small animals. Playing on the quilt may be a simulated hunting behavior.
In general, cats like to bump into quilts maybe because they find it fun, or because they feel happy when doing so and relaxation, or because they are simulating hunting behavior.