Well this title is not a thumb rule, but if you are in the Web business like the way I am, then this certainly holds true for you.
My own experience is that the general client is least bothered about how strong a website you might have built in terms of web technologies, but unless your website is visually appealing, they do not care much about your site's technical aspect. Now that does not mean you develop a lousy website, very poor in technical standars and which is just visually appealing! But if your website is strong in the technical side and also graphically chic, it holds a lot of value for your product.