[sbuk]

>>"tl;dr: both how it looks and how it works are secondary to what if offers the customer"

The product (App/Pizza/Car/Suppository/Whatever) still needs designing; i.e. a problem exists that needs solving. However you want to phrase it, a problem is solved by designing, be it using established patterns or generating new solutions. How it looks and how it works should be intrinsic to what a product offers. None of the elements are mutually exclusive.