What you're discussing is the age old clash of descriptivism and prescriptivism. And, well, this, basically.
Louis Menand ("Thumbspeak", The New Yorker, 10/20/2008) aims a gibe at my profession:
"[P]rofessional linguists, almost universally, do not believe that any naturally occurring changes in the language can be bad."
As a representative of the species, I can testify that this is false. Rather, we believe that moral and aesthetic judgments about language should be based on facts, not on ignorant and solipsistic gut reactions.
Unfortunately, it's precisely ignorant and solipsistic gut reactions that tend to dominate discussions of English usage, and so linguists and other sensible people are forced to spend time trying to clear things up. This sometimes leads to the false impression that we have no stylistic opinions or grammatical judgments.
Let me decline to enlist on either side of this concocted War of the 'Scriptivists, and speak instead on behalf of a third group: the Rational People. We believe in making value judgements about language use: some writers are better than others, and even good writers sometimes make poor choices and outright mistakes. But we also believe in the value of facts, both about linguistic history and about current usage. We're unwilling to accept the assertions of self-appointed linguistic authorities about what is "right" and "wrong" in standard formal English, if these assertions conflict with the way that the best writers write. We understand that vernacular forms of English are not faulty or degenerate approximations to the formal standard — instead, they're just, well, vernacular. We're willing to accept, as Horace was, that new words and structures, and new uses of old words and structures, can be a valuable addition even to the most formal linguistic registers.
In a nutshell: we don't worship our own prejudices, and we're more curious than censorious.
There's a characteristic psychological dynamic here. People like Mr. Rose see a bit of writing or talk that irks them. They're not interested in analyzing the problematic usage, tracing its history, looking at its contemporary distribution and its relationship to other phenomenon, exploring the nature of their own reaction to it — no, they just want to make those people stop, dammit. And they want the rest of us to join them in howling at the miscreants. If we suggest a more temperate investigation, or dare to question whether a crime has been committed at all, they turn their wrath on us as well. In fact, our analytic detachment seems to annoy them even more than the object of their jihad does.