Web design is basically a process of coding and graphic design is a much different process. We have logic (coding) on one side and creation (creativity) on the other side. They both play an important role in the creation of a great looking website. Many web designers underestimated the importance of graphic design knowledge in designing websites as a result, they struggle to create "attractive" websites. The visual part of a website can really make a basic brochure type website look more valuable.
Here are some key points that why graphic design does play an important part in web designing.
Visual Connection – Everyone has heard the saying 'a picture is worth a thousand words', well the same can be said about the visual aspects of your site. You can usually connect with a person viewing the site much better with simple graphical designs. I've been to pages where I can feel an emotional state created by seeing this amazing design. People like to see nice things and they typically return again to see it some more. Graphic design will help you make an extra connection, which is vital in this business.
Usability – A lot of web designers miss out on the most important aspect of a website – usability. The person viewing the site needs to be able to use it in the way it was intended to be used. That means they have to be able to navigate and find the contents that they are looking for. Having good visual communication knowledge will make this a lot simpler than what regular coding will do. It's important to note that you can sometimes go overboard with graphics, but if you keep it within a specific range, graphics can enhance the usability of a website.
As you can see there are many benefits of having good graphic design knowledge if you are a web designer, or planning to become one.