It's important at the higher levels of the game more so than the youth levels, in my opinion. For college and pro players, it's another way to measure and track progress in the development of lean mass that's more accurate and helpful than a scale. While there are all sorts of methods to measure BF%, some more accurate than others, I think any method is fine as long as the tool used to measure is consistent over time. Even the pinch test for BF in 3-5 places works well.
12-14% BF is what pro pitchers are expected to be.
I was 210 lbs and 11.7%-12.3% in college as a stater and then 225-230 and 10% in pro ball as a closer... this indicates I gained 15+ pounds of muscle in my first year of pro ball (gained mostly in the off-season) in a healthy way. That's the benefit of measuring BF%.