I guess I haven't worked on a project important enough where the history is more important than the current state. Usually it's more like it might be useful to gain perspective by looking at the history, only to find it was a conflicted merge or the comment contained no useful info anyway ("Clean up", or "Fix this feature").

Even if it tried really hard to document the purpose of the change, I've rarely gotten more from a commit message than the content of the code changes in the commit.