By writing content that is original and of high quality your articles will be indexed in the main pages of the search engines and not in the supplemental results (which is what happens to duplicate content). Original content will keep your website from being dropped from the search engines.
Quality articles need to be keyword optimized. Most visitors to your blog or website arrived there by typing in one or more keywords related to the topic of your website in a search engine. Research your keywords carefully. Well optimized articles have a much better chance of getting positioned in the top 30 results in the search engines. Giving you free organic search engine traffic.
Blog posts should have a word count of at least 200 words. Website articles should have a minimum 500 words per page.
Your readers will enjoy the well written content and return often to read new content. Happy readers will recommend your website to others.
Blogs and websites will link back to your site. These incoming links will make you known as a trusted authority. Incoming links from relevant websites will help increase your Google PageRank.
Really good content will be mentioned on social networking and bookmarking sites which may bring more traffic than your server can handle.
Link to other related articles on your site to get more page views. Rinse and repeat. Meaning, keep adding content to your site regularly, this way people will keep coming back and new visitors will stay longer.
The extra time spent on writing quality content is well worth it.