I'm thinking along the lines of what Quora does.
For two reasons:
- Out of common decency. If someone edits the content of my post so that it substantively improves my answer, I'd like to just say thanks.
- So those who do so can be recognized somehow for providing excellent edits.
Since editing badges just reflect volume of edits, I'm not sure (2) is satisfied to the same extent as an explicit thank you.
With that said (1) is my primary focus in this request. - it's not a "why edit?" question - what I'm asking, simple and trivial as it may be, boils down to: "why can't I thank you for doing so?"