How does it feel like loosing a lot of hard work you forgot to save?
What if your computer shuts down when your article is not saved?
That's why I'm suggesting this: the Auto-save funtion.
Yes, you've heard it: akin to that of Google Mail, the Auto-save function automatically saves a draft of your work for later. The draft will stay a draft until you Publish it into any wiki.
It would be on by default, but those who never forget to save their works (and are brave enough) can turn it off (and back on).