The reason is that each form of writing has its own style. News is delivered AP style, in short, informational paragraphs with the meat of the story at the top. Blogging is personable, friendly and often opinionated. Ad copy is short and persuasive. White papers are long; they describe a problem and provide the solution. But, regardless, each and every category is content, and each style writers master makes them more valuable and in demand.
Businesses focused on expanding their reach to more customers will want to pay attention to the increase in the volume of visitors, as well as the quality of those interactions. Traditional measures of volume include the number of visitors to a page and number of emails collected, while time spent on page and click-through to other pages/ photos are good indicators for engagement.