I have completely opposite opinion on this.
Writing commit messages is one of these mundane chores I’d gladly delegate to LLMs which are very very good at this kind of thing.
I mean, if you really know you code, you know it, there is no much value in reinforcing it in your head one more time via writing comprehensive commit messages - it’s a waste of time, imho.
Man, 99% of non-bug-fix commits don't have a why other than "advance the current task".
Almost all commits live in tandem with some large feature or change being made. The reason for absolutely all of them is the same - build the thing .
Then write that and link to the current task. That's the why. You don't need an LLM for that.
Sounds like you haven't been working long enough to forget your decisions, which you WILL do eventually. In such cases, where you're looking at code you wrote 10 years ago and you find a weird line, when you view the git blame and read the commit message, you'll be very thankful that you explain not just "what" you did, but "why" you did this, something an AI will have a very hard time doing.
You don't have to if you don't want to, but if you think "this commit message is just a summary of the changes made", you'll never write a useful commit message.
Neither the code nor the AI know WHY a commit it being made.
This context should at the very least be linked.