People don't read ancient manuscripts but recent reeditions of old works. Those can be done using new spellings, as they are in, for example, Spanish. Nobody reads the Quixote, the Mio Cid or the Amadis with the Spanish orthography of their times.
And this is actually a loss. I have a fantastic edition of the Song of Roland with facing pages in Modern English and Medieval French, and there are nuances that would be lost in a straight translation to either Modern English or Modern French.