Good design.
When a visitor enters your web site, it must catch their interest immediately. It should be inviting, attractive, interesting, and informative, as well as convey a professional image. Your visitor will take from 10 to 20 seconds to decide if your site is worth staying around long enough to find out what you have to offer. There are so many other sites out there, they can instantly click to another one. They won't be back. Opportunity lost. Like they say, "You never get a second chance to make a first impression."
For many people, your site will be their ONLY introduction to you, so it better do its job well. Your web site should look as good as you do.