>her books are easy to read for lack of a better description (though this latter features in much contemporary writing).

Maybe linguistic evolution is playing a role? Contemporary writing is easiest to read because it's written in contemporary English?

I also think The Elements of Style had a real and positive influence, in terms of e.g. sentences getting shorter: https://www.lesswrong.com/posts/xYn3CKir4bTMzY5eb/why-have-s...