Well Dave, I'm just winging it here trying to listen to my gut, but it seemed to me that the way the angles are, that if the brace continued on over the tone bar brace, that you would have too much bracing too close together on the bass side, and I wanted to keep the bass side looser. It also dies out before getting to the tone bar. My impression of tone bars is that you want them to carry the vibrations from end to end, which is why the ladders bridge over them, so the only thing I have touching the tone bars is the bridge plate.
Now I may well be full of it,

, but this how I'm thinking you want the tone bars to work.
Shooting from the hip,
Joe