Remember when the Aero Board Racer debuted and everyone was up in arms over the vertical back seam?
It really works here; I'd call it elegant. Beautiful back.
I think that with deeper understanding of jacket construction, thoughts on this matter have changed. Not sure about the forum, but in general people used to think that having to cut the leather is smaller panels is "cheaper".
While in mall brands, it generally would be the case, with high end manufacturers, a beautifully made seam is actually a feature, sign of impeccable workmanship.