I'm don't think I agree with the idea that the way of entering edit mode should determine the way I leave it.
cmd/ctrl-S and cmd/ctrl-w are not manually more complicated or simpler than one another.
But it is more complicated to say at the outset, I will edit a single line only and then exit therefore I will hit return in this pane, or I will edit for a while so I will use cmd/ctrl-U. Perhaps complicated is the wrong word - its rather that its not necessarily correct. I'll get into my note and then realise that I have other corrections to make that I didn't think of, or that I'll want to add more than I thought.
Once one is in edit mode apart from content there are three basic operations : save, exit with save, exit with discard. One might add others like discard but stay open and so on but ... Until now the first two were clearly distinguished. I don't recall how discard works but normally some form cmd-Z works and then a cancel to throw the changes since the last save. But making the first two behave the same way just because of how I started my edit session does not make intuitive sense to me. Perhaps I am missing something.
So I support reverting the functionality but I don't know why the change was made so I don't know if there is, or was thought to be, a good reason to do it.