Given the unexpected attention being paid to my annoyance at "Happy Holidays," I ought to clarify things a bit.
First, I should repeat (but with emphasis added) that "If you tell me 'Happy Holidays,' I confess I'll get a bit annoyed because of its generic air, but I'll just assume that you're trying to play it safe -- often a very good strategy in social relations. Plus why be churlish about someone wishing you a happy anything?" It doesn't bug me much, and when I say "I confess," I mean I'm confessing it to you in this post; I certainly wouldn't berate or even glower at someone who is telling me "Happy Holidays."
Second, my chief concern about it is precisely its "generic air": "Holidays" is an abstract, general term that has much less directly evocative force than the concrete, specific "Christmas." Christmas has a wide array of immediate connotations to it, some quite vivid, and my sense is that for 90+% of the public (including many people who aren't religiously Christian) they are highly positive: Family gatherings, presents, traditions, and the like. The term "holidays" is also positive, but with many fewer immediate connotations, precisely because it covers such a wide territory.
In recognizing this, I've been influenced by Deirdre McCloskey's excellent Economical Writing: "A good general rule of words is Be Concrete. A singular word is more concrete than a plural (compare 'Singular words are more concrete than plurals'). Definiteness is concrete. Prefer Pepperidge Farm to bread, bread to widgets, and widgets to X.... In a paper on Australia the phrase 'sheep and wheat' would do just fine in place of 'natural resource-oriented exports.'" To shift from the happy to the macabre, I recall a paper of mine in which I was recounting a particular incident, and wrote "Two years later, Harriet committed suicide." Editing, I realized that it should read, "Two years later, Harriet drowned herself." It's not that this conveys much more practically useful information; but the concreteness makes the statement more vivid and immediately accessible.
Returning to "Happy Holidays," I am indeed bothered (as Eric correctly assumed) by the reason from the change from "Merry Christmas" to "Happy Holidays"; I believe it was prompted by an excessive concern about offending people who should not reasonably be offended by the old term. But if the change could have happened with no cost, I would be much less bothered. What bothers me more is precisely that the change was costly: It strikes me that a certain amount of emotional immediacy was lost in the change from Merry Christmas to Happy Holidays.
To be sure, though, the loss wasn't vast. And I sympathize with those who want to avoid offending or alienating listeners, even if I think the feeling of offense or alienation on the part of the listeners is unjustified, so I wouldn't hold the change against those who are now saying "Happy Holidays." That's part of why I'm only a bit annoyed by the phrase. But I am indeed a bit annoyed by it, by what it portends for some such changes in the future, and what it symbolizes about some such changes in the past.