grammar ... is now incresingly in the hands of everyone and is being led by pop-stars, sports "personalities", TV presenters, all aided by the media. But it is still grammar, and to be not only understood but thought to be a good commuinicator, you have to keep up with whatever the current rules are.

I agree--right up until the last phrase. I suppose, like so many things, what we can tolerate is subjective. I can tolerate sentences ending in a preposition, for ex., but I am absolutely not going to let someone who says "ain't got no" set the standard for me; I don't care how famous they are.