I care about the aesthetics and the convenience that the tool provides. git-repo at least has a simple command to get all the latest stuff (repo sync). Git submodules is a mess in this regard. Just look at this stack overflow thread:
https://stackoverflow.com/questions/1030169/pull-latest-chan...
People are confused at how to do THE most basic command that you’d have to do every single day with a multi-repo environment. There’s debating in the comments about what flags you should actually use. No thanks.
There’s a lot of room for improvement in this space. git-repo isn’t widely used outside of aosp. Lots of organizations are struggling with proper tooling for this type of setup.