Easier to Learn
It is well accepted in the snow sports community that it is easier to learn how to ski than it is to learn how to snowboard. It’s just a matter of your normal stance as a person, you stand with two feet apart facing forward, just like on skis. Snowboarding makes you strap both feet to a plank and face sideways going down, it just takes more to get used to it. And who wants to put in extra effort?
Kids Can Start Earlier
The recommended earliest start for kids on skis is about 3 years old, my brother even first put his feet on skis at about 2 years old (cool kid points). The recommended age for kids to start on a snowboard is about 5 years old, just due to balance and coordination issues. If you want your kids to be the best and get the most practice time in, they’ve got to be skiers.