Is "Bon appétit" Déclassé?

In an op-ed in today's NY Times, an American expat living in France is scolded that "bon appétit" is not an expression used by people who are “well brought-up.” Here's what I've observed in several trips to France:

The French are always wishing someone a bon something. When you enter a shop you are greeted with bonjour; when you leave it, bonne journée (have a nice day). In the afternoon, you may be wished a bon après-midi or its more loquacious cousin, passez un bon après-midi. Late in the afternoon, come some magical time that only the French know, bonjour becomes bonsoir when you come and bonne soirée when you go. In between, at dinner, you may be wished bon appétit before you eat and bonne continuation during. At the end of the meal, the waiter might wish you a bonne fin de repas or even (and this one is a little too clinical for my taste) a bonne fin de digestion.

Well, if bon appétit is déclassé, I can't imagine what the writer's stuck-up friends would make of bonne fin de digestion!