The primary reason for this used to solely be as link bait, but these days Google itself knows what a good piece of content looks like.
Structure of Good SEO Content
Machines reading content can attempt to analyze the words and structure of a page to understand if it is thorough, readable, and providing useful information. Here are some of the technical elements that a machine reader may evaluate while trying to study the quality of a given web page:- Use of headers (h2, h3, etc..)
- Lists (ordered or unordered)
- Length of content
- Inclusion of pictures, video, and/or other media
- Correct grammar and spelling
- Varied sentence structure
Checking the boxes won't necessarily make boring content in to something that generates user enthusiasm, however, and links are still very important for a successful SEO campaign!
If you research your market and your keywords and provide a great user experience, you won't have to worry all that much about the SEO.