Some time ago, when disks where really slow or files where even stored on external, even slower devices (cassettes, floppy disks) it may have made sense to specify when exactly to save a file because you had to wait a considerable amount of time. However with modern harddrives and usb sticks and whatnot, this concern is out of the way. I hate it when I have to save files manually in any program, especially in text editors. First thing I do is look for an autosave plugin.
However, programs should allow as many levels of undo as possible and keep the history even after restarting a session.
vim can do this