Since the SEO landscape is always changing, it is smart business to keep evolving as well. Now that websites have moved from a static marketing piece, to a dynamic presentation and now to a mobile campaign...it is important to keep moving forward!
We are in the age of minute man advertising. With Twitter, Facebook, Pinterest, etc...we look for dynamic content to come to us. Having a blog for your business is not only SMART business, but it is becoming truly necessary.
From a marketing standpoint, sending out current content is great SEO as well...keywords as titles, categories, post types and tags, will ensure you a first page position with GOOGLE!
Think of it this way, every time you send out a new blog post, it is like dropping off a brochure to everyone in your list!!