The combination of mtn biking of frames with relatively shallow seat tube angles, and the desire to be lighter than whatever came before has led to the majority of modern posts, such as Thomson to have the center of the saddle cradle directly over the post (no setback). Most modern 2-bolt posts are this way, which also has the advantage of being easy to make.

I'm not a fan, especially because I'm mainly a road cyclist, and find reasonable setback necessary to correct saddle position. To my knowledge most modern set back posts tend to be single bolt designs these days (except Thomson, which gets it's setback by bending the post back 3" down) tend to be of single bolt design, again because it's lighter and easier to make. I prefer the old 2 bolt rocker designs like on the original Campy post from the sixties, but in all fairness, once the saddle is adjusted, you never bother with again, so I can live with the (IMO) crappy 1 bolt systems, if that's what it takes to have the correct setback.