Companies don't like it when people take apart their products to see how they work. They would like it if their products were treated as black boxes. Many software shrink-wrap licenses even bind you contractually to not reverse engineer the software. Hex editors and disassemblers, which are common programmer tools, are not allowed. Usually, if someone finds out how a product works by reverse engineering, the product will be less valuable.
Companies think they have everything to lose with reverse engineering.
This may be true, but the rest of the world has much to gain. It scans small bar codes found in magazines and catalogs into your computer, then sends you to a Web site, which gives you more information. Linux programmers, ever eager to get a new device to work with the Linux operating system, took the thing apart. They reverse engineered the encoding the device used and found out how it worked. This allowed them to write their own applications for the device.