This would be useful in cases where you matched a release with 12/12 files, but then realized you have an extra / 13th bonus track that was still listed under Unclustered files and no release with that bonus track already exists in musicbrainz.

Currently if you want to submit that release to musicbrainz, you have to move everything back to the (un)clustered view to submit all files as a new release. It would be nicer if you can do that immediately from the right view.
This means that you first create/submit a new release and then replace the current selected release with the newly created release.

For background see https://community.metabrainz.org/t/feature-suggestions-after-matching-a-huge-messed-up-folder/712286