In reply to Frank4short:
caveat - I am totally guessing here...........
1)It might be something to do with biometrics. Height of head above the ground correlates with centre of gravity correlates with balance - therefore a low height of head above the ground (well actually C of G would be around the torso, but that's not the point) with a long reach is better.
2) Weight is important in climbing. I'd rather have reach through (relatively speaking) lightweight arms, rather than a heavier long torso.
Just a couple of ideas to put into the pot........