This simple idea is so fun there is a reason so many people do it every year. This is the first year I attempted to cut paper snowflakes with my oldest, who is now four years old. It was great cutting practice for him. I didn't have him fold his paper very many times and I drew really big shapes and easy lines, but he really surprised me at how well he did. Before this activity cutting on lines seemed hard and frustrating for him, but he loves the idea of snow, and making snow flakes was really motivating for him. I really like his big snow flake.
Here is a really good tutorial for how to fold and cut really pretty 6 pointed snow flakes (good for older kids) and in
this post is an idea for making snow flakes out of coffee filters.
You should definitely spend a little time cutting out at least a snowflake or two with your preschooler. And then you should put them up by some family Christmas pictures from your youth, or not, that is just what I did with mine.
But if you have a picture where your husband looks like the cutest baby elf you have ever seen, you should definitely put that picture up every Christmas to admire the cuteness, and put a paper snowflake by it just for good measure. :)