Now that #2172 is merged to address #648 (yay!), I'd like to propose a breaking change to switch the default from keeping untracked files to removing them.

It seems like the main reason that --remove-untracked was chosen over --keep-untracked was for backwards compatibility concerns, per #648 (comment). #648 (comment) and other comments on that issue generally lean towards remove-by-default as the preferred behavior.

I filed this as a tracking issue under the assumption that it'll have to wait around for v2.

See also the philosophically-related #3248.