I have a Note 3 from 2013, so I definitely understand going for the bigger screen, but when I played with a 6s in store I realized that my phone is actually a bit too big and the 4.7 inch size works fine. It's hard to one hand text and is just a bit awkward. The new camera is a non-issue for me. I doubt I would see any real world benefits between the two. Anyway, the bokeh thing comes later as a software update *shrug*
But to the OP, yeah I think they just produced more of the 4.7 inch phone. Can't speak to the real demand.