I wonder if people choosing the 6plus are just more sedentary - and fatter too? The kind of people that just sit around on the couch all day, or at the desk all day, at eat. I just can't see how very active people wouldn't prefer as small a device as possible.
I highly doubt 60% of all iPhone users sit around on the couch all day.
I am an 'active' person and I ordered a 6 Plus. The bigger screen just worked for me more than the 4,7 inch.