There are many reasons to redesign a website that might not be obvious to naked eye of a layperson. What most websites owners need to understand is that most of the present websites are not compliant to the W3C standards and were not designed keeping in mind the "latest" browsers. Other reasons have a commercial aspect to it. One continuously needs to upgrade his business websites to attract more and more clients, and especially with the fast changing trends of online business, you need a website that looks contemporary.