To really determine how important web design is all it takes is some time to visit different websites on the web. Pay close attention to the type of experiences you have when doing this.
The first thing that will probably draw your attention is what you see visually. If you are on a site that has 
pleasing colours and doesn’t look like a rainbow then you will probably find this enjoyable. That doesn’t mean that various colours cannot be used in web design. It means they have to be chosen and used carefully. If the colours are too glaring then your intent will be to leave as quickly as possible.
Most of the colour that catches the eye first is that which is used in the background. Then following this will be the colours that are found in the different types of images. These can be comprised of a lot of different colours and if the background on the site is too flashy then it will detract from the images.
The images are meant to tell a visual story or deliver a message. Banners are also another visual component that makes up part of web design.