The feature has been used all the time since we launched the forum and people tend to quote all and remove the text afterwards I guess.
People are going crazy over this missing feature on our forum and I can see why, it’s a way they are used to operate their posts. Without quoting it gets very difficult to read many persons idea in a subject, for a more Q&A style of topics like here on meta it makes sense removing it.
Does the feature still exist and we can enable it with css or so? Or are we required to go all crazy and fork the entire discourse project? 
Edit: Also, why did you not add this to the release notes? This is quite a major change for a community. I’ve been googling since the report came in and tried to figure out why it was gone, and checked the settings etc. In our forum we could completely remove the emojjis (never used by anyone), but that one is well covered in the release notes 