I think people tend to overthink this. The only thing I need from a commit message is what you did and why you did it. (One might be implicit from the other). If there's more than that, you might be committing too much at once. People hardly ever go over commit history unless something got fucked up, and then those are the things you're interested in. Whenever people get OCD about the form or rules I cringe.
As others have observed, these comments are used for auto-documentation, for reporting, and for merge requests. Its handy to be able to categorize them, to schedule and organize these activities.
I feel like things like "auto documentation" and "automated reporting" are code words for "things that superficially sound useful that in reality no human should ever use to make an actual decision". So in that context, well formed commit messages are very important for supporting bureaucratic nonsense. My feeling is that if you want to publish a change log, you should do that by hand while keeping the intended audience in mind, and if you want to review the performance of people, "metrics" are extremely game-able and instead the work should be considered as a whole.
