I've noticed that each of the WTF BB poomsae are more difficult to do. I get that (ideally) one should be able to perform more complicated poomsae as one progresses. However, I've come to realize that noone reaches 9th Dan until age 53 at the earilest. The upper forms have jump spinning crescents & jump side kicks. I know that not all can do those techniques well as they get older. So my question is: "Why are those techniques in those upper ranks poomsae?"