Content Management can be either your site's greatest asset or greatest downfall. To make sure that your website runs smoothly and lives up to its potential once it has been completed, it is important to keep the content fresh. For instance in a competitive industry where prices of products change frequently, consumers return frequently to websites that provide them current information, and stop visiting sites where the prices are out of date.
If your site is informational with mostly text pages (along the line of an online brochure) you don't need to worry about content management as there will probably be only occasional changes. However, if content, such as product price, need to change frequently, you need to have your website updated on a regular basis to keep the site current and visitors interested.