From Jared Sinclair’s excellent “Form Follows Function” Is More Complicated Than iOS 7 Thinks, in which he explains why some of the skeuomorphic elements of iOS 1-6 were actually useful:

On iOS, putting function before form is not as simple as paring down icons to a strict grid and color palette. There are functions beyond literal communication that iOS designers must balance. Making icons warm and inviting serves many deeper purposes. It builds your confidence in the device. It makes you feel in control. It sets your mind and thumbs at ease. It communicates through feeling and memory, and when done well, resonates with human experience in a way that PCs never could.

There have been a few other defences of appropriate skeuomorphic elements recently. From Kevin Suttle’s Frame of Reference:

There has been quite a bit of confusion over what skeuomorphism is. Many define it as “creating digital products or interfaces that resemble their physical counterparts”. The goal of skeuomorphic style was to leverage our pre-existing affordances and lend a healthy amount of familiarity and confidence to digital interfaces.

And from Dan Wineman’s must-read Look, and Feel:

Affordances are the baby to skeuomorphism’s bathwater. When they engage our instincts just right, they create an emotional bond, and the unfamiliar becomes inviting. Without them, it’s just pictures under glass. It makes no difference how flat, how deep, how minimal, or how ornate the look-and-feel is if it can’t show us, when we look, how to feel.

So, as it turns out, good design is (still) all about affordance.