|A well designed website doesn't guarantee its success. In the virtual business world, a site success is measured in term of traffic and visit to client conversion.
A site can be very functional, eyes pleasing, easy to navigate, beautiful, etc. But if it does not convert, it is just a well designed website and nothing more.
I know sites that aren't well designed, however are a success within their niche market, and vice versa, I also know sites that are well designed (in a complete sense of the term), however are not successful. In this case, you should try to accomplish both goals, good design and success.
Usually website designers do not have a clue about search engine optimization and Internet marketing, which anyone can learn just by searching for free readily available info about that subject on the web.
A person who can learn a fair deal of Internet marketing and SEO can build a simple website and be more successful than a person that hire a site designer to build his/her site and doesn't know a clue about effective SEO and Internet marketing methods and strategies.