The question is do you want to rank higher in search engines? Yes a blog built on your website can be a very vital tool. The reason is because it’s content always changing and being added to. For an example if you offer a service and you provide information about your product on your website, you’re not going to change that information everyday matter of fact it would be ludicrous to change that information everyday, but your blog gives you that opportunity. Everyday you can expound on your products and give more and more information daily to help spread the word about your website. A blog is your playground and it gives you the ability to continue creating unique content which brings new visitors.
With a blog your able to be a little bit more free with how you communicate to your audience. All in all having a blog on your website drives traffic and increases your rankings with major search engines (google, bing, yahoo).