Indeed, the old style of Japanese--known as Kobun--is not a popular subject in schools there, and it's not hard to figure out why: it would be like trying to teach Americans the equivalent of Old English. In fact, when the Hirohito (Emperor Showa) read the rescript that accepted the terms of the Potsdam Declaration for the surrender of Japan in that famous speech, the majority of Japanese had serious difficulties understanding it because it was essentially a speech in the same language as a Noh dramatic play, which uses Kobun as the spoken language.
By “Old English”, do you mean Anglo-Saxon or something like Chaucer’s Middle English? Those were two very different tongues in and of themselves.
Kobun is an odd one. Any idea why it’s heavier on kana than modern Japanese?