Better because you don't have to spend as much time preparing for a run down a slope. Snowboarders have to fiddle with straps and by the time their down your already down the hill. Also, Snowboards take up a lot of space whenever you are going on a chair lift especially if its a 2 person chairlift .
I don't think there is really an argument that explains how it is better per se but it simply is. Skying is more expensive, it has more equipment and thus is more cumbersome, and it really just sucks and is for old people who don't like to do anything difficult.