In general, I'm in favor of having those physical skills well-described in the rules.
In general, they don't come up.
That being said, I've used it before. In D&D or the like it's a niche skill on the level of Use Magic Device or Sense Motive. In other systems, it might be the subset of a general athletic skill, which I think is a better way of doing things all around.
It's as important as Jump, Tumble, and Climb.How important is Balance in a system to your game experience?