For many things, function is more important than form. But in today’s busy world, we seldom have time to investigate the function of competing products. That’s why we use the form as a way to judge function; in other words, we judge the book by its cover.
That’s why, in terms of making a product, it’s important to consider both the design and the delivery. The design of a product will determine what it’s used for and how useful it is, whereas the delivery of a product will determine its uptake.
Delivery should complement the design. For example, a word processing product should look like a word processor. There are certain motifs that humans expect from products of a particular genre, and without good reason, one should not deviate from those motifs.
At the same time, design must complement the delivery. Features that are hard to use or difficult to access from the UI should be given a lower priority than features that will be centrepieces of the UI.
It is this latter point that most products fail to achieve. Developers have a natural aversion to letting the delivery drive the design. We have an idea in mind of what the product should do, and what it shouldn’t. We think that the UI should match that, and we reject that we should match what our product does with the UI.
But delivery is just as important as design. So it makes good business sense to let it take the front seat once in a while.