In the big scheme of things - or even the little scheme of things - it's likely not that important to defend the honor of Christmas from being truncated from the famous "twelve days" to one. But there feels something in it symbolic, as if we Christians are picking up secular clues. The length of the holiday is not what the big retailers determine it to be but what the Church does. After the 25th no one is buying Christmas gifts any more, so there's no incentive for the materialistic concerns to promote the holiday.
Perhaps though instead of seeing it in conspiratorial terms it's simply that we are accustomed to see celebrations as single days, be they birthdays, anniversaries, president days, etc... Unlike the Middle Ages, there's much less a custom of multiple days attached to single remembrance.