I’ve heard a phrase used recently a number of times and it has struck a cord. The phase was [and I paraphrase]:
“… the product should be like a Swan, serene above water, legs kicking frantically below…“
The insinuation is that although there is work occurring below the waterline that work is compact and simple and should not impact the product; the serene Swan. This is a very valid view to hold and one that also conveys the some separation between form and function.
However, most modern systems do not approach the elegance of a Swan. A more adept metaphor is probably that of the Iceberg. There is typically a lot more below the water line (i.e. not visible to the user) than above the water line.
The waterline on our Iceberg is somewhat movable also as different people may see varying amounts of it. But most importantly an Iceberg and a Swan have very different maneuverability characteristics.
Some projects are Swans and some are Icebergs. Neither is implicitly better, but if you mix the 2 up; you’re going to be in big trouble.