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. 

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.