Simple but pretty common use case: If you're ever looking at some pre-existing code and thinking "I don't really get why it's written like this?", you can get a lot out of looking through the git blame/history.

Often "weird design" is there for historic reasons around stuff like backwards compatibility. If your project has a well managed commit log, you can find the notes of whoever implemented it, possibly even with their motivation for doing so.

At the very least, you can find out who wrote that code and ask them about it.

There's a tonne of data in git histories - this article was shared a few months back and is an awesome example of some things you can do with git history: https://piechowski.io/post/git-commands-before-reading-code/