Commit messages are very rarely read. I'd say it's well worth committing anything that compiles (that can only help bisection, which is a much more important use for history than human readability). Even a non-compiling commit isn't really a hindrance - if it doesn't compile mark it as unknown (you're using an automated bisect script that does that, right?), and you end up with the same result as if that commit hadn't been made.