Nowadays, it's not enough to just have a website. You need to grab and hold people's attention. So it's important to know how to do that.
Before designing can begin it's vital that your designer understands your business goals, culture, and what your users want. That last one is the most important. Businesses often think they know what their users want; so they only focus on making something look good. Success hinges on meeting user needs, with an excellent user experience, so this cannot be overlooked.
Your customers need to FEEL connected to your website to buy things from you.
If you're trying to beat your competition, enhance how your users feel about your company, products and brand as a whole. You can't force them to press that 'Buy' button, but you can make them trust you, with a solid and intuitive website.
User Experience is a vast science of vital interactions between a website and users. UX isn't fluff you add onto a pretty website. It's the core foundation and psychological difference between an average and outstanding product. For more on usability, read some articles by the father of UX, Don Norman.