Advent is a season of anticipation, not a season to "celebrate" anything. It's not even part of the Christmas season. The modern consumerism of Christmas comes to an end on December 25th, but that's actually the first day of a joyous season that extends through the time after Epiphany and doesn't come to a formal end until February 2nd.
Advent’s part of the Christmas cycle, broadly speaking...and no, we are not singing the Gloria and are wearing violet, but if there were no celebration in the season, we wouldn’t have Gaudete Sunday. Some looking forward seems appropriate. Like we have the presepio/Nativity set up, but of course the stable is unoccupied.
And it’s full of pretty stellar feast days: Immaculate Conception, St. Nicholas, St. Lucy. Kinda hard to keep celebration out of it.