I think what I have learned in this thread is this: Some people have chosen their battlefield right here. It is of the utmost importance to push their opinion about the classification of Die Hard onto the general public. High profile polls leading the first attack.
I remember when assholes tried to start a crusade over Star Wars "not" being science fiction.
The only fact that any poll establishes is the fact that that's how the poll came out. It does not prove anything about the topic of the poll.
Most of the movies that are regarded as "Christmas movies" are not really about Christmas, but have the Christmas season as a background. "Die Hard" takes place around Christmas, and has Christmas decorations and music in the background. Because of that, it evokes thoughts of Christmas. Maybe, in some sense, that makes it a Christmas movie. But for those who insist that a movie must be about Christmas to be a Christmas movie, it's not a Christmas movie.
I think that's an accurate summary of the situation.
I separate films out as being actual Christmas movies and movies merely set during the Christmas season (perhaps we can call them "Christmas-ish" movies).
Elf, A Christmas Story and Miracle on 34th Street are Christmas movies. Die Hard, Gremlins and It's a Wonderful Life are Christmas-ish.