Search engine optimization is really important for any blog or website because a good optimized blog will get loads of organic traffic from search engines and it can count up to 60-70% of your total traffic. Having Site map for a blog is one of the important part of Search Engine optimization as Site Maps allow search engines to reach all the content of your blog with ease and thus benefits in better placement in the search engines.
WordPress doesn’t generate Site Map on it’s own. However, we would love to have this feature come default in next versions. There are plugins which can generate Site Map for you else there are simple tricks through which we can Generate a Site Map.