Another reason why you need a blog is that a blog-less website is mostly stale – there’s minimal update, not much new information, and not much interaction from the customers. A blog will make your website more customer and reader-friendly. It will also make your website more Google-friendly. Google loves new information. New articles = new information = Google love. Simple, right?
I would like to add that for information products, a lot of the time it’s pretty easy to rank for “information product review”. I recently did a review of a popular ebook that is a month long discipline program. I went about it by doing the actual program and documenting everything. At the end of the month I wrote up a 2700 word article summing up the whole experience.