First of all, let me say I'm sorry for reviving this topic, and I actually really like how nice it looks to have curly quotes in docstrings.

That said, right now a lot of the curly quotes are false-positives, and I keep running into them every couple of weeks. Here's an example from js-jsx-mode:

  (add-hook ’js-jsx-mode-hook #’set-jsx-indentation)

As long as these false-positives are numerous enough to be encountered frequently, think this makes for a worse user experience than simply keeping the old grave+straight-quote combination.
As such, it is my opinion that this (very well-intended) feature is not quite ready for release at is.

I suggest we either fix a large portion of these false positives, or we change the default value of  text-quoting-style to `grave' on the release branch (we can maintain the nil value on the master branch and mark this commit so it won't be merged back).