Hi Clint,
I agree that writing about your art process, motivations, etc is so important - and not just from a marketing perspective. For me putting my art experience into words helps me to recognize and focus on what matters to me as an artist. And it can even be a protection against getting caught up in art trends (which may be fun, but be too much of a diversion from whatever it is that makes you, yourself, a particular artist)
I also have a question for you about the difference between a blog and a newsletter. I've been writing what I think of as a "blog" but I email it to nearly 300 people who have signed up. Which seems to mean that it is a newsletter. I also post links to new blog(?) posts on Facebook and Twitter. So, do I have a hybrid of sorts? I believe my blog can be searched for and my past posts are easily found. Can you clarify, or let me know if you think this is an effective marketing effort? I have sold work both to folks who know me and signed up for my blog as well as folks who heard about my work via other social media. So it seems to be working.