Scratching is a perfectly normal feline behavior.
Although scratching does serve to shorten and condition the claws, the primary reasons that cats scratch are to mark their territory and to stretch. Cats may also threaten or play with a swipe of their paws. With a good understanding of cat behavior and a little bit of effort, it should be possible to prevent or avoid most clawing problems, even for those cats that live exclusively indoors. Cats that spend most of their time indoors, however, will usually require an area for indoor scratching, climbing, and play. It is impractical and unfair to expect cats to stop scratching entirely.