Because it will save your butt in times like this:
Sure, some super human stuff there, but balance versatility training will help everyone become more ready to handle unexpected happenings.
Get suddenly thrown in the back seat while descending a steep pitch? No sweat, you have the skills needed to not stress about it, continue your turn while back there, and simply return back to the center of you skis at your leisure, all in complete comfort and control. Fall on your inside ski? No need to freak, or prepare for the imminent fall. Just keep on skiing on that ski, it's actually kind of fun.
Expanding your balance skills, and your balance comfort zone is empowering. It inspires confidence, and allows you to carefreely venture into new terrain and experiment with new drills and skills that would send lesser skilled skiers running for their foxhole. Here's some of the balance development drills that will lead you to that level of versatility and confidence.