I think statues of famous people in action are not a good idea. Many of our heroes have been captured in a formal pose - literally posing and being themselves. The sculptor has embued Nelson, etc., with the quality of solemnity and statespersonship, and they, it feels, are consciously giving their dignity to us - as a tribute to nationhood, or community.
If it's a generic figure representing flight, joy or dance, then movement, but I think famous people are better captured standing still and poised and being themselves. I don't think it's easy to tell a story in bronze, and keep it formal. ( Ok for 'thr lovers' etc but not for a very famous person whose statue will be standing there for centuries).
As a poster said, Diana had so many mannerisms, such as crouching down, and leaning forward to a person, and looking up through her fringe - head on one side, that it would have been good to choose such a moment, as long as it's a static one.