RSS stands for "Really Simple Syndication". Submitting RSS feeds is a good way to increase your subscribers, visitors who visit the concerned directories may enjoy reading and thus decide to visit the parent websites. Advertising your RSS feeds can actually help your search engine rankings, both inadvertently and directly.
Also, there can arise a possibility where interesting feeds may be syndicated by fellow webmasters within the same niche. This can bring traffic from their website and at the same time there are possibilities of getting one way links too. Make sure your RSS feeds are directly relevant to the content of your site. The more relevant, unique, and important the information contained in your RSS feeds, the better.