The biggest factor with brace height for me is arm clearance.

I shoot my best with just a slight bend in my bow arm - with my shoulders square or slightly pointing right of the target. This puts the most of the force into the large shoulder bones and I hold much steadier. This is also the best way for me to use back tension. A low brace always catches my clothing when I shoot like this.

Yes I can open up my shoulder alignment, and turn my elbow out more to accept a lower brace - but my shooting, like most who do this will suffer IMO.