Web design is actually a very important part of making a website.
The webdesigner has to "build a bridge" between the user and the code provided by the webdeveloper.
The webdesign has give the user as much information as possible without making it confusing for the user to read. it has to be as fast as possible, so the user doesn't have to navigate between pages. And you have to think about how the user will get from x to y as fast as possible without navigating to far away from the main/front page.
the design should also be very catchy so the user is likely to stay, and [sign up, buy stuff, contact you, share the page]
so webdesign is very important and it is also very hard to make it right!