The most likely reason you'd replace your vehicle center console is because of wear over time, or some part of it broke due to misuse or wear. It's not a mechanical component, so replacing it isn't terribly critical in terms of safety or being able to drive the vehicle. It can be a nuisance though if you really would like to store something under the lid and it doesn't latch properly, or is missing altogether. Another location that receives lots of wear besides the lid is near the cup holders and the shift lever, if it's located in the center console and not on the steering column. Constantly placing cups, bottles, and whatever other small objects into the cup holders and change recesses will eventually wear in those areas. You may notice discoloration, thin spots, and maybe even cracks. If there is cracks near the shift lever, that could allow dirt and debris to penetrate into the shift lever mechanism and cause more problems. Although replacing the center console isn't typically an emergency situation, to have use of all its features and be sure all of its parts work properly, it's a good idea to replace it whenever the need arises.
Your vehicle's center console is designed to be ergonomic and functional since it's a piece that you'll be using to store things and usually rest your arm on depending on your driving style. It usually consists of a large section between the seats to hold larger items such as power cables, disc cases, documents, etc. Above that, there's sometimes a small portion just under the lid. The lid is where some people like to rest their arm while driving, so it's usually made with a plush material. In the front of the center console is usually some cup holders and then a shift lever and/or parking brake lever.
Replacing a center console isn't an easy task. As with most interior parts, the majority of the attachment points are probably hidden from view, under the carpet, or other plastic components. Below are some very basic instructions for replacing it.