On the other end of the spectrum you get ImageMagick useless commit messages[0].
That extreme aside, I'd rather have commit messages that delve into the why-and-how the commit alters the behavior to the better rather than cryptic message as 'Replace invalid ASCII char'. Now we have documented reasoning and thought process that can aid future debugging. They can also be beneficial for new devs hacking on the project, or students learning how to implement and improve systems.
Personally, I enjoy reading these. The Go commits often have commit messages like these, and they are shared on HN often for a reason. They're learning material. They can't go on a wiki because they're tied to particular set of changes in a particular point in history. They also can't be comments on the code because they're tied to particular lines in different files, and code comments can only cover a set of consecutive lines in one file.
One recent example I could find is this[1]. Yeah, it fixes ^Z, but why didn't the old approach work? Why did it work for some time then didn't? How did it change? Why is this commit optimal, if it is? All of this along with scenarios to reproduce the issue.
Give me your life story anytime over cryptic message.
[0] https://github.com/ImageMagick/ImageMagick/commits/master
[1] https://github.com/golang/go/commit/610d522189ed3fcf0d298609...