or they could have shaved off the bezels??
something please to make it different from what we already have.
that could have been a greater selling point
I guess there is a sort of arrogance to this; saying that you could have "most" of 6S's internals - provided it's in an old body.
My guess is Apple never wanted to re-invent the 4' iPhone just upgrade the old 5s. Maybe its them testing the water since the released the 5c.
I'm thinking they'd give a decent 4' IP a go and see how sales go, if all does well maybe a big upgrade next cycle round.