As a web designer, you should design your websites to give your visitors the greatest ease of use, the best impression and most important of all a welcoming experience. It doesn't matter if you had the greatest product in the whole world -- if your website is poorly done you won't be able to sell even one copy of it because visitors will be driven off your website by the lousy design.
When I'm talking about a "good design", I'm not only talking about a good graphical design. A professional web design will be able to point out that there are many components which contribute to a good