Software like OneNote has shown that auto-save can be implemented, and it works just as well (or better) as the manual save button / CTRL+S.
Anyways everything that you work on you want saved. Its just if you're trying out something destructive that you would close without saving.
So from a programmers/usability perspective, why is the manual "save" feature still seen in virtually all software today? Is it because everyone is too lazy to implement "auto-save" whenever data gets modified?
And is it a good idea for us implement auto-save, at least to start some traction in our specific industry and amongst our competitors?
The save button is a well-known, comfortable UI feature that everyone from Jon Skeet to grandma is familiar with. If you got rid of it, it would be like removing the close button on a window for some people. Granted, they would eventually get used to it, but some people would not understand that their data has been saved automatically.
Also, if you're autosaving on the web, not only are you taking up a lot of space on your server with all those instances, you're also using up a lot of bandwidth with periodical saves. At least with manual save, you are only using the space and bandwidth when the user intends, which can be more infrequent, thus saving bandwidth. The advantage, of course, to autosaving is the retention of work should something go awry.
Check the definition of "skeuomorph" :)