The unchecking of this option doesn't actually do anything. You'll still continue to upload saves unfortunately and I think this may be a bug, I'm not really sure.
Agreed. I do not have bandwidth issues, but I just didn't want to save my games to Steam cloud. Mainly because if you save it in the cloud, it wasn't clear when that save would be deleted. It does make "Save and Quit" not an option anymore, though, as I don't know how long I need to wait in order to quit after saving to end a session.
While cross-save is a nice idea, it would also be nice to not be required to do it.