Web Design isn't just about the look of a website. Good Website Design also considers how a visitor uses a site and guides them to the content they need then presents an appropriate call to action to ensure that we get what we need from the site.
I often see websites with very confusing menu structures. Sometimes with drop down menus that go 3 or 4 levels deep. It's frustrating enough just finding what you are looking for let alone actually getting to it. Have you ever had this experience on your laptop? Navigating a drop down menu with a touch pad mouse, you get to the level you need and a slight mis-movement of the mouse collapses the whole menu and you have to start again.
I also land on the home page of many websites and struggle to work out what to do from there. How do I get to the content I want? The web designer hasn't provided any clear calls to action, all I see is "Welcome to our website. We've been in business for x years...". I have to suffer through that complicated menu to find what I need. It's just too easy to give up and hit the back button.