It's almost certainly for the upcoming Steam release. When those go well, it can be incredibly lucrative for a dev, so it makes sense to take a little time to redo some things that might stick out negatively to a brand new player.I don't get the need to go back and rework. Especially on games with such large histories. I don't want to have to go back and replay hours of previous play to view a few "improved" scenes. I would prefer less delay in releasing new material, as well.
And when reworks cancel previous saves, creating errors due to changes in codes, I have deleted games. I wouldn't do that with DS, but I would freeze an archived version and quit downloading updates.