Companies invest a lot of money in developing their products. If pirates are able to copy the intellectual property of legitimate companies, it will hurt the entire industry. The people who worked to develop these products need to be paid for their work. Most people will not buy illegal copies anyway because they are known to be low quaity.
Knock-offs, items that are made to imitate a brand product, should be illegal to be both produced and sold in markets. The United States has enacted a law involving copyright, where it is illegal to reproduce copyrighted items. Brand name products are copyrighted, and even if a knock-off is not of the same quality or an exact replica, a product being made to physically imitate a well-known product for the purpose of selling it as the well-known product should be illegal to both produce and sell.