May I inquire what your suggestion for this would be?
Reason I ask it is because ALL smartphone manufacturers have this same exact problem, so it doesn't appear as if it's just a result of complacency on Apple's part.
Whether we like to admit it or not, smartphones have largely settled on a dominant design (thin slab of glass with a camera on the back) which means there is a lot less room to innovate (and hence differentiate) the product from others.
Until new technologies emerge, it seems likely that we're stuck in the era of incremental change where differentiation will be increasingly difficult and economies of scale all the more important.