Jody Bottum proposes that, to the extent that we feel a poverty of Christmas spirit, it is due to a loss of Advent as an antecedent:

What Advent is, really, is a discipline: a way of forming anticipation and channeling it toward its goal. There’s a flicker of rose on the third Sunday—Gaudete!, that day’s Mass begins:  Rejoice!—but then it’s back to the dark purple that is the mark of the season in liturgical churches. And what those somber vestments symbolize is the deeply penitential design of Advent. Nothing we can do earns us the gift of Christmas, any more than Lent earns us Easter. But a season of contrition and sacrifice prepares us to understand and feel something about just how great the gift is when at last the day itself arrives. 

More than any other holiday, Christmas seems to need its setting in the church year, for without it we have a diminishment of language, a diminishment of culture, and a diminishment of imagination. The Jesse trees and the Advent calendars, St. Martin’s Fast and St. Nicholas’ Feast, Gaudete Sunday, the childless crèches, the candle wreaths, the vigil of Christmas Eve: They give a shape to the anticipation of the season. They discipline the ideas and emotions that otherwise would shake themselves to pieces, like a flywheel wobbling wilder and wilder till it finally snaps off its axle. …

We’ve reached a point in American culture where any recovery of both Christmas and Advent probably require a breaking of the economic hysteria that a “healthy American economy” pretends to require and a spirit of sacramental withdraw that authentic Christian encounter necessitates. That is, the culture of more and more and more that precedes Christmas stands in opposition to the spirit of less that characterizes Advent and the discipline that Bottum speaks to.

Bottum also shares his own nostalgia, and wonders whether the strange difference in time’s passage was just something of his (or any) childhood, or whether that’s something we stand at risk of losing generally as only a thin patina of Christmas (as a sacramental holy day) remains to cover the new reality of Christmas (as an economic holiday) that dominates December:

When I was little—ah, the nostalgia of the childhood memoir—I always felt that the days right before Christmas were a time somehow out of time. Christmas Eve, especially, and the arrival of Christmas itself at midnight: The hours moved in ways different from their passage in ordinary time, and the sense of impending completion was somehow like a flavor even to the air we breathed. 

I’ve noticed in recent years, however, that the feeling comes over me more rarely than it used to, and for shorter bits of time. I have to pursue the sense of wonder, the taste in the air, and cling to it self-consciously. Even for me, the endless roar of untethered Christmas anticipation is close to drowning out the disciplined anticipation of Advent. And when Christmas itself arrives, it has begun to seem a day not all that different from any other. Oh, yes, church and home to a big dinner. Presents for the children. A set of decorations. But nothing special, really. 

It is this that Advent, rightly kept, would prevent—the thing, in fact, it is designed to halt. Through all the preparatory readings, through all the genealogical Jesse trees, the somber candles on the wreaths, the vigils, and the hymns, Advent keeps Christmas on Christmas Day: a fulfillment, a perfection, of what had gone before. I shall see him, but not now: I shall behold him, but not nigh.

The “Christmas season” begins on Christmas and lasts through the Epiphany, but in the secular and popular experience the Christmas season begins at Thanksgiving and is largely economic—and so it has little of any transcendent value, as far as I can see. It’s worth reading Bottum’s entire piece.