I know I've gone thru that with my blog posts as well. Part of what keeps me going is when people whose music I feature end up telling me how great it was to have their music shared in such a fashion as my blog. I'm pretty sure I've gotten away from my original goal of only writing about the music. At some point I will come back around to focusing only on the music, but it's a journey.

If your blog is making you happy then why worry about whether it's useful? Right?