//fyi @joaomoreno
We always suggest to run Undo Last Commit and then Commit again instead, it's more explicit.
Every user is different you can't make option standard but we must make a lot of options to do thing and let the user choose this is standard of any programming language ... #let_user_choose @joaomoreno
Feel free to write an extension that provides that command.
Do we really need to construct the whole (sometimes complicated) commit again and write commit message (sometimes long and elaborate) again just to fix a typo?
The commit message gets populated with the last commit message, when Undoing the last commit.
Atom 1.18 beta just introduced a proper Git panel similar to the one present in VSCode. This panel provides a simple Amend checkbox beside commit button, as shown in the picture below:

IMHO, it's a really simple thing (from the UI point of view, at least) to be included in VSCode Git panel, and a more simple solution than "undo last commit & re-commit" steps.
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Atom 1.18 beta just introduced a proper Git panel similar to the one present in VSCode. This panel provides a simple Amend checkbox beside commit button, as shown in the picture below:

IMHO, it's a really simple thing (from the UI point of view, at least) to be included in VSCode Git panel, and a more simple solution than "undo last commit & re-commit" steps.