Except that this does not violate the principle of least surprise at all. I expect that files I edit are saved at some point, somewhere, iCloud makes perfect s

Except that this does not violate the principle of least surprise at all. I expect that files I edit are saved at some point, somewhere, iCloud makes perfect sense in that it allows me to pick up where I left off on any device. Not only that, but Mavericks had the same behaviour for unsaved files as far as I remember.