Perhaps he did not know, but I find that a lot of developers, especially those not using GUIs, end up using -m every single time and writing poor commit messages. With Magit, at least in my experience, you are more inclined to write better commits.
If you give developers a "lazy" option, a lot will default to it, which isn't ideal. -m is an alternative for a quick commit and end up being front and center when using the CLI.
If you give developers a "lazy" option, a lot will default to it, which isn't ideal. -m is an alternative for a quick commit and end up being front and center when using the CLI.