I agree (somewhat) with those that will argue with me about my thoughts that every dropshipping product type site needs a blog.  Some topics just are not "blog-worthy" like say for example a site dropshipping sunglasses.  It could be very difficult to blog about sunglasses everyday I agree. 

BUT, if you are able to find an angle, and find a way to blog about even the simplest of products then you will be gaining an edge over the competition.  The number one factor for sites that outrank their competition is the content.  If your site (that has an often updated blog) is going up against a site that has had the same information on it for the last several years then you will have more of the love that Google will dish out (when it comes to search engine rankings, cache and page rank).   This is really the number one reason;  Your site will have the "edge" over your competition in regards to Google and the possibility of gaining higher rankings.

Getting back to my example of sunglasses here are just a few ideas off the top of my head (that you may not have thought of) that could be good blog posts.

• Talk about the Sun and the UV Rays etc. and why your eyes need protection.
• Talk about safety while doing something like mowing the lawn.
• Talk about movie stars and the glasses they wear.
• Talk about funny sunglass styles in years past?

Do you see where I am going with this?  There are many more ideas that I have running in my head with sunglasses, but this is to just give you a good start to  thinking about how you could go about adding valuable content to your website (via a blog) in order to help you with your search engine rankings.