[andosteinmetz]

Having worked with people whose commit messages are along the lines of "update function", my experience has been that when you're trying to find where a bug was introduced, it's quite helpful to review (good) commit messages to quickly get a sense of what concerns a commit was addressing, and what code it's likely to have touched.

Speaking for myself, I also find that writing a good commit message is useful in helping me think about what work I've just completed and whether the changes I'm committing form a logical group.

Granted, there are all kinds of workflows and I can vaguely imagine some in which commit messages are redundant, but still, I don't think it makes sense to generalize the statement.