Unique content has always been one of the factors that the major search engines like Google, Yahoo and Bing consider as the foremost factor when they decide how to rank a blog or website page in their search index.
Many people who enter the competitive world of internet marketing or simply just want to let the world know about their hobby or part time business look to the area of free search engine traffic to get visitors to their sites. Let me explain, you have people who spend most of their time promoting all kind of websites in all manor of large and small niche markets and they all want to get to that elusive number 1 spot on the front page of Google which will drive obscene amounts of web visitors to their sites.
If you want free traffic for your sites then it is a major consideration on posting new and unique articles to your website so that when people search for a phrase or keyword on the search engines they will happen to come across your information ideally on the very first page for their search and therefore click on the link that leads to you and not to your competitors.