The note above is why people don't like this feature, but that being said to me it's personally essential. I typo all the time and rewrite what I said to fix typos all the time. The original note is still visible and any good client should implement a way to see it (like amethyst does), then there isn't a problem. The way that element displays it (you can see the history with all the diffs) is good enough for every single use case in my opinion.