Long story, short: SEO. Google and other search engines love content on your site. It tells them who they need to show your site to. Even better is very targeted local content (think your city vs. a neighborhood in your city).
Featured community pages provide an easy, quick way for you to create extremely local and targeted content. Not only is this content a way to attract and impress visitors to your site, it also boosts your SEO. When people search for a specific neighborhood, building, or area of town, it is this type of content that helps your site rank high on those search results.