Hi BSmith. And a very Merry Christmas to you.
My great-grandparents, who came from a long line of Primitive Methodists, were married on December 25th, 1879, in Victoria (Australia). Apparently it was more common in most denominations than we can imagine.
The best explanation I've read is that Christmas in those days was not as important as Easter. If you look at Bishops' Transcripts, you will rarely find a marriage in March or April around the time of Easter. The reason for that is apparently because in those days Easter was a much more solemn occasion as it celebrated Jesus' death and resurrection, and it would be inappropriate to have any other celebration at that time.
Have a happy New Year.
Peter