It's a design element, plain and simple. There's no scientific secrets or magic potions involved, a cuemaker does it because "he can". Some do it better than others. lol
It's kinda interesting to me that CMD mentioned it possibly allowing less flex.
I've never even considered that possible reason. I've always thought it was used to reduce the amount of weight/mass up front or maybe because of overall balance,or by customer request. Tommy D.
i think it's more for the look of the cue. I had a cue made recently that has an elphoryn joint. i went with the half joint purely for looks. The cue I had made was Amboyna with Ebony points and i didn't want the joint to overtake the look of the cue. With the half joint the cues look seems more balanced to me. It seems sometimes when I see cues with Ivory or Ivory substitute full joints it looks like the joint is a mile long.