The physical interface is an intrinsic part of the design of any eurorack module, including artistic elements. If you actually use these, then you quickly tire of menu diving for simple options, and only modules that do very particular things make it worth the bother. For everything else, the layout must be accessible, memorable, understandable, and not too crowded. And it helps if the visual of the thing conjures up memories of how it sounds or what it does.