Design gets a visitor's attention; words decide what they do next. People don't read websites; they scan them, looking for answers to three questions: what is this, is it for me, and what should I do now. If the copy answers those in the first few seconds, they stay. If it makes them work it out, most of them leave.
The most common problem we see isn't bad writing; it's writing about the business instead of for the customer. "We are a leading company with years of experience" tells a visitor nothing. "We design kitchens that fit small apartments" tells them in one line whether they're in the right place. That shift, from what you want to say to what they need to hear, is most of what good copywriting is.
