Of coarse you should do it! Just because you do it doesn’t mean you have to add it to your portfolio.
Put some thought into it and get them something nice, they can put on, or in, Christmas cards. You could go all the way and use a couple of cans of snow if you pay attention to the background — i.e. it has to look cold, no trees in full leaf.
If results are inconsistent, practice, practice, practice! Bless anyone willing to stand in front of your camera.