So the problem with literally becoming *yet another* alternative to “very” is that we no longer have a word which means “no really, I mean this thing actually happened, it’s not just a strong metaphor”. So our language has become less expressive because this particular modification.
This is a good and wise restriction (or, gasp!, prescription) on word meaning and usage, the violation of which does impair clear communication and is entirely unnecessary. As machineghost points out, we already have numerous words and phrases to give emphasis to a statement, even to the point of hyperbole, and using literally to do so degrades the impact of this word when it is appropriate.
The non-necessity of using literally to give emphasis to a statement via hyperbole reminds me of Mark Twain’s admonition against using very to give emphasis to your writing. Good writing typically gets its point across effectively without adding this emphasizer, so it is either unnecessary or is the sign of weak writing.
The same lesson can be applied to hyperbolic, non-literal literally in probably every imaginable context. Take the much written-about instance of British soccer commentator Jamie Redknapp saying “David Silva literally floats around the pitch.” Or another one mentioned in that article, “literally in another galaxy”. The columnist uses history to justify his concession that hyperbolic literally is right and proper, but I’ve always seen history as only a part of any discussion about grammar and usage. Luckily, we in our wisdom can see the error of the ways of those writers of centuries past and can see how the misuse of literally impairs usage by weakening its impact in proper contexts. Writers who used or continue to use it for hyperbolic, metaphoric effect were/are writing ineffectively and impairing the effectiveness of this word in literal contexts.
On top of weakening literally in its correct uses and leaving us with no word to take its place as meaning “no really, I mean this thing actually happened, it’s not just a strong metaphor”, hyperbolic literally is literally entirely unnecessary. If you’re using literally in an obviously hyperbolic, unrealistic, out-of-this-world, impossible, or fantastical metaphor, then the metaphor should do all the work of having a strong impact on the audience, without being “strengthened” by the misleading addition of literally. What, if you say an athlete floats around the pitch or that some people seem to be in another galaxy on a political debate, these don’t have a strong enough impact on the audience, so you have to add literally before it to sort of fool the audience into thinking, “Oh!—maybe he does mean literally—oh, no, of course he doesn’t, but he must be really, really, doubly, triply, extra serious, then!”
This is weak hyperbole for writers and speakers who either can’t write or speak effectively or are so dense/see their audience as so dense that they cannot be satisfied with mere hyperbole. Stan Carey writes about this linguistic inflation and sort of manages to come down on the right side, by the end of the column. He does quote writer/composer Anthony Burgess with a sentiment echoed by machineghost above:
A ‘colossal’ film can only be bettered by a ‘super-colossal’ one; soon the hyperbolic forces ruin all meaning. If moderately tuneful pop songs are described as ‘fabulous’, what terms can be used to evaluate Beethoven’s Ninth Symphony?
This page, Not everything is epic, is amusing and spot on.
The literally vs. figuratively debate provides a good example of wise, beneficial prescriptive rules. The rule is: don’t use literally when you mean its exact opposite, figuratively. Breaking it encourages sloppy thinking, writing, and speaking, it insults the audience as if they aren’t smart enough to recognize the hyperbole, and it reduces the effectiveness of literally in its correct uses.