I'm going to disagree with you on both counts. While maintaining backward compatibility is a good thing, there is often a cost, and very often that cost is too high. In this case, maintaining cruft and additional code complexity in order to maintain a feature that should never be used anyway simply isn't worth it to the authors/maintainers of the software in question.
I precise my point : it's a backward incompatible release, so it's version number should be 5.0, and not 4.2. See [semver] (http://semver.org/).
