To borrow from Roland Barthes: some languages are writerly and others are readerly. The choice is whether the speaker (written, vocal, or rude bodily noises) is responsible for the accuracy of the language and by extension for making the language unambiguously understandable for the reader, or if the language is sufficiently simplified that it forces the reader to be the arbiter of the author’s intent?
“Who” versus “Whom” is a good example. Do I immediately know “who” is committing the action and “whom” is being acted upon, or do I have to guess “who” is “who”?
When Othello says Desdemona is to die “presently”, he doesn’t mean “in a while” he means now – immediately. This ideally needs a gloss in printed versions of the play, to prevent misunderstanding: the meaning of the word has clearly changed considerably since Shakespeare’s day. How and why this change has come about, I do not know, but it’s a fair guess, I think, that it changed not because someone somewhere decreed the change, but because people who spoke and wrote in English began to use the word differently (possibly out of ignorance); and because this different usage soon caught on, and the older meaning of the word became obsolete. This may or may not be a loss to the English language: I would say it isn’t, but wouldn’t argue…
A Celebration of Reading 