Generally speaking, writing more words allows for more phrases to be picked up by the search engines. Often enough, these phrases can exist in the content without being listed in the title. However, keywords and phrases in the title will get better rankings than those that are nested in the content.
In a nutshell, more is not always better in the article itself, but more articles is always better. The simplest way to achieve this is to have a blog or a content management system with all sorts of categories, sections and content.
Even though small articles and blog posts can be very effective, quality will always count. People are not dumb. If they are smart enough or have been lucky enough to have the opportunity to read, they will normally know the difference between the good writing and the bad. Also, your writing on your website will be a maker or breaker for repeat visitors.