@justinfrank my primary motivation was writing for myself in the past, what do I wish I could have read when I started the project. in retrospect many things are obvious /after/ you learn the thing, but what wasn't? in that way, the material being obvious is actually the goal.
(personally I don't like the idea of research having to be Big And Impressive to be worthy)
you could argue that there might be plenty of materials already that explain the background, but think about the numerous different topics and courses you've taken. there have certainly been materials that make more sense based on the way a professor presents it, based on the way the text explains it, based on the examples used, and so on. but you have a unique perspective worth sharing, with the cherry on top of having this perspective allowed you to make a contribution, no matter how small you might assume it is.
this helped me a lot, but it may have only worked for me because it appealed to my teaching side. I like the puzzle of figuring out how to explain The Thing in a new intuitive way.