Dissatisfaction with skeuomorphism leads to the question, if we're against it, what are we for?
The obvious refrain was to design in a way true to the nature of the medium. See the Good Design principles (1950) for this formally acknowledged as a key precept of, it would seem to follow, good design.
I admit I might have missed a brilliant treatise here and there, but in general I have heard responding silence on the matter of what is the nature of, say, a touchscreen mobile phone.
Certainly we can abide by the OS principles, but even that seems too tactical. Many seem to insist that there is no nature to follow — the glass is too featureless and the bounds too infinite. Impossible, I say. Nothing is without flaw out limit.
As I type this, I can see some wall tiles, clearly meant to look hands painted, and just as clearly actually screen printed reproductions. The shapes are technically there, but at insufficient fidelity, so the directionality of the strokes gives way to the reality of the halftone grid.
Our maybe that's too decorative. What about paper? Lots of designed experiences are still on paper. At it's best (I think here of intaglio and letterpress techniques) design and execution for aper meet the goals of the design while allowing the medium to , and to enhance the final work. An offset reproduction of a letterpress poster is not the same thing, as there's a physicality that moves past the flat page. Designers on paper are aware that ink sits on top and changes the paper itself by being run through the press. That ink should be applied in certain orders to achieve specific effects. We work with the process and medium, not against it.
How do we do that with digital design, for glowing screens? I haven't worked it all out, but for starters, there is dimensionality. The display layer is behind the glass, often some distance behind it. Even on a flat device without a bezel (use any iPhone as an exemplar) the interface is not flat, but behind the interaction layer.
And it's not perfect. Even setting aside glare and so on, the screen does not illuminate perfectly evenly. Oh, our conscious brains adjust for this and we don't notice it really, but it's there, and we subconsciously perceive it certainly. To see it, try making the screen one solid color and then take a photo of it (a screenshot won't work). The variation in brightness is not an artifact though it may be exaggerated by the camera.
When we design perfectly flat interfaces, we're designing for flat interaction and perfectly-smooth reproduction which does not exist. Without direct evidence, I believe that this is why subtle gradients and shadows behind elements (bars, strips, buttons) work well. They emphasize the nature of the phone display – color variation and depth of interaction.
Or maybe not.
More to come, if and as I figure it out.