Centaurus,
My bet is the steady increase over the years of additional read-backs published in AIP, is probably due more to arse-covering in the legal sense rather than a history of mis-understanding by pilots.
You bet wrong. Readbacks were generally much less than present (and much better documented) until ICAO R/T was introduced by the Dick Smith Internationalisation brigade a few years ago.
Nothing wrong with being friendly on the radio...as long as it doesn't "force" a perhaps busy controller to make an extra transmission to reply in kind.