To add, I have issues with the attitude shown by the blog author.
If you use the development branch, you can't raise hell when there's a breaking change: it's to be expected!
Then it's fine to disagree on some change and discuss this. I read the email thread, and I do not see "arrogance". Just strong disagreement. So yes, converging will take a bit of time... Calling publicly someone "arrogant" for not folding back to your view, and trying to raise the crowd (a good part of whom won't read the thread to make their own opinion) looks like bullying to me.
Saying that his patch to make the change optional has been disregarded, when it was rejected because it not only made the change optional (that would have been OK, and a patch for this asked for) but removed other changes is not honest.
Lastly, pointing out one person to blame when the whole discussion is done with the Emacs maintainers in the loop is also a no-go in my book.
As a close to 30 years Emacs user, thank you to all its contributors! (and to Thierry, as long time Helm user) May their skin by thick, it's unfortunately sometimes needed :-P