Pet Peeve: Farewell to Direct-Address Commas

I hardly feel right even being peevish about this error because everyone I know commits it. Or perhaps I should say that everyone who emails me or texts me commits it.

And yet.

Well, darn it all, it does bug me: the casual casting off of my dear friend the direct-address comma. What the heck am I yammering about? So glad you asked. Compare these two greetings:

Hello, Holmes. How are you doing today?
Cheerio Watson. Not at all well, thanks.

According to Chicago and every other style book on the planet, Watson has written his greeting correctly, while Holmes slacks off in his usual comma-hating manner. (Unfair. Yes. Sorry.) Holmes ought to have written:

Cheerio, Watson.

Just as when someone types an email to me, it should open with:

Hi, Claire,
Hi, Claire!
Hey, Anal Grammar Lady!
Hello, you stuck-up so-and-so,

But everyone omits that comma. And while I'm willing to let it slide (really? Is that what you're doing?), I'm afraid this habit may leak into other forms of prose. So even if your emails aren't perfect--and whose are?--make sure your more formal prose is correct:

"I think I've solved the case myself, Holmes," said Watson proudly.
"Don't be ridiculous, Watson," Holmes answered. "You couldn't have, old chap. That's my job."
"I'm sorry, my friend, but you're wrong this time. While you were off at the bookshop, I compared the prints I lifted with your database. And I think, dear boy, that the killer is ..."
"Oh, do be quiet, you nattering hobbit. If I wanted the help of amateurs, I'd have consulted the cat."

And so forth.