The challenge is not in just capturing the moment, but also having the correct exposure and frame/composition ready. Many photographers have a sense of the moment, but not the framing. The aesthetic sense of framing is commonly referred to as the "eye". So someone with a good "eye" will have interesting photos. I rarely crop a photo more than 10-30% of the area. In most cases what you see is the way the shot was taken.
Solos and duets are easy to shoot but corps work is a challenge, due to coordination of the dancers and size of formations.
Having said that, most photographers with digital cameras, can shoot close to 200 photos in a 20-30 min piece (depending on the style ad choreography). The final yield of "good" photos is smaller. I have noticed that in Ballet solos and duets, 20% of the photos are not usable. In corps work, 50-60% of the photos have to be thrown away. Artistic directors, and marketing eliminate more photos due to their stringent requirements.
My first experience of loving the work of a dance photographer was with Martha Swope, who created unforgettable b&w images of the early decades of the NYCB. (Not to mention that great photo of Balanchine watching Mourka, his cat, as he leaping into a truly prodigious tour en l'air.) (1)
I also admire the work done by Steven Caras, first at NYCB, and now for Miami City Ballet. Caras was a NYCB dancer whose photographic interests were encouraged by Balanchine. He has an uncanny sympathy for the way the dancer's body moves. I guess his most famous photo is not actually of a dance. It's Balanchine's last curtain call ("last bow") at the NY State Theater on closing night, 1982. (2)
Who are the dance photographer's you most admire? And what makes them special?
-- (1) Taper, Balanchine, p. 244.
-- (2) Tributes: Celebrating Fifty Years of New York City Ballet, pp. 112-113.