I have a blog, but I rarely write about my Etsy shop. It sends very little traffic my way (like, 1, 2 views a day). However, on those rare days I do post about my shop, my views from the blog skyrocket.
The lack of traffic doesn't really bother me so much, because I've found a little niche and I enjoy writing and sharing.
It could wind up being completely different for you, you could see tons of traffic and sales coming from your blog. You'll never know unless you try it :)
So if starting a blog is something you really want to do, I say go for it. It can never hurt to get yourself out there in any way possible, right? Best of luck and happy blogging!