If you place a track on top (or better as a replacement) of the old track the segments that are not needed anymore are deleted automatically. (Does not always work. Sometimes i still need to delete the old track manually. There the feature that the delete key only deletes single segments is needed.)
So instead of breaking the track and dragging the newly created corners just redraw that part of the track using the interactive router.
If you have interactive drag enabled (and move a track) kicad breaks the track automatically if it encounters an unmovable obstacle. (I like this more than the push option of the interactive router.)
Are these the usecases where you need break track or did i misunderstand its usefulness?