Language evolution (langolution?)

I want to pose a question: How long do we hang onto "proper" grammar when 99% of people do not use it anymore? I tend to be a stick-in-the-mud on this one, but I am also aware that language evolves. There is no question to that. So is there a point in trying to hold onto the "rules," or do we simply go with the linguistic flow?

I am wrestling with this issue again (okay, perhaps "wrestling" is a bit too strong of a word) because of something written by one of my favorite columnists (Peggy Noonan, who has an absolutely lovely style no matter what you think of her views). To give some background, Noonan once introduced the word "integritous" into her column in an attempt to coin an adjective for "integrity." I agreed that it was a needed word and wish that it had caught on.

So I have always appreciated her use of language (and tendency to coin new words!). But now, she has written this in her current article:

This is one reason the media is important. (Not "are important." Language evolves; usage changes; people vote with their tongues. It's not the correct "return to normality"; it's the incorrect "return to normalcy." It's not "the media are" it's "the media is." People see the media as one big thing.)

My instinct is to scream, "No! Media ARE! Media ARE! Medium IS, but media ARE! And for that matter, datum IS, but data ARE!"

My parents raised me with these distinctions clearly drilled into my brain. I actually almost wrote a letter to the board of the ACT, because when I took the test (back in... goodness... 1998?), the science section included the use of "data" as a singular noun.

Do we fight it, or do we give in?