i think its because they are more kinds of jibbing styles to choose from on a snowboard, they go from 50-50 all the way to blunt slides(somehow, but as for skiing, we have tail, nose and rail slide, thats why we do so many swtich-ups, spin-ons, spin-offs, because we only have 3 rail slides to choose from, so you have to try and find a way to be creative, and not to the same old thing. Also, snowboarding, like you said would be alot easier to do all these things, but they have so many diferent kid of jibs to choose from, so they dont need to do all these swtich 270 on 450 off, they can just go straight tail slide and it will still look good.
Listen to it, my friends band
Bloodninja: My turnips listen for the soft cry of your love. My insides turn to celery as I unleash my warm and sticky cauliflower of love.