Originally Posted by ThermionicScott

I think you're imagining a lot more going on than really is. If it were important at all to have exactly equal lengths of thicker sections on each side of the thinner center, I'd think more of the spokes I'd purchased over the years would have had them.

The main reason to have the elbow and threaded sections thicker than the center is because they are slightly weakened by the forming and the threading. (Looking at it the other way, a straight-gauge spoke is stronger in the center than it needs to be, compared to the ends.) The thick section between the elbow and center section is probably just due to manufacturing, and any remaining thicker section between the center and the threaded end is so that you don't have to swage every spoke length a different amount.