> Perhaps more to the point, Japan, which uses Chinese characters for nouns, adjectives, adverbs, and verb-roots, has a very high literacy rate.

While literacy might be high, there's been a stream of articles over the years in Japanese media noting that literacy in kanji (the component of Japanese based on Chinese characters) in particular has been steadily declining, even among the highly educated; e.g. http://www.japantimes.co.jp/news/2013/07/03/national/kanji-w...