The comments gives a link to a recent talk about the motivation for using Rust in Git: https://github.com/bk2204/talk-rust-in-git/blob/dev/presenta...

I wouldn't agree with all of those reasons, but it's very definitely not "just for the sake of it." One of the better reasons so many people look to writing some things in Rust is that we now have pretty ample evidence than trying to write a binary file format parser in C is a cornucopia of CVEs that are just simply absent in Rust, and the excuse of "well, but a sufficiently smart programmer doesn't write bugs in C" doesn't cut it anymore.