I simply don't believe that you have small hands and can pick up the phone and tap on any icon on a full screen of icons with one hand, without jiggling the phone around awkwardly in your hand.
I still have a 5S that I love, but just bought a new iPod touch for my wife for her car - mainly to use Apple Music.
Have thought for a while that an end point for the iPhone design is to put it in the iPod touch design. (Yes, I know there;s never any end point for design, but as long as there has been the iPod touch it has felt like that was the optimum and preferred design for the phone, but the phone was subject to limitations that prevented that from happening.)
They seem pretty close now, but I still really don't like the lines across the back (yes, I know - a necessary evil) (yes, I know, not literally evil).
So in that sense it might make sense - introduce a 4" phone which is essentially the iPod touch with a phone, and release the new top end ones later in the year in a very similar design, but in the more traditional iPhone colours.
Or something. Who knows.
I never said i use it totally 1 handed all the time, i use 2 hands when necessary and i havent got a problem with it