I don't think it's okay to hate on skeuomorphs in shipping products, as the author does here. It's a designer-centric rather than user-centric way of looking at things, and it's bad news for users when value judgments that aren't derived from the user experience are allowed to affect real products. Going by his definition of skeuomorphs, a drop-down menu is not a skeuomorph. A spinner (like the ones used in the iPhone to set a timer or an alarm) is a skeuomorph. That distinction has nothing whatsoever to do with which one is more usable in a given context.

Design space is dizzyingly unconstrained, and finding an optimal design is an intractable problem. A skeuomorph (sticking to the definition in play here) has taken its initial design from a particular source, a physical object. Odds are that the optimal design does not resemble that physical object. So what? Physical objects are a legitimate source of design ideas. Starting with a highly optimized solution to a similar, more tightly constrained problem is a common and effective pattern for generating good solutions to an intractable problem.

Another way of saying "hating on skeuomorphs" is "stigmatizing skeuomorphs," and the likely outcome of that is that designers, mindful of their professional image, will tend to eschew skeuomorphs in favor of inferior non-skeuomorphic designs until the winds shift back. (Isn't that the point of hating on skeuomorphs? To influence which designs are perceived as good or bad?) All that means to users is that they will be forced to use inferior designs because of a point of fashion they aren't even aware of. Another way of saying it is that analyzing whether a design is a skeuomorph or not is like analyzing a musician's influences: it might give you a clue to whether the creator keeps up with current trends, but it won't tell you anything about whether the product is good or not.

Sure, it's legitimate to say that other sources of inspiration should be mined as well. Constraining a problem to non-skeuomorphic solutions is a legitimate creative exercise, just like constraining the problem in any other way. It's a creative exercise, though. It isn't a legitimate rule of thumb for designing products any more than "use skeuomorphs!" is a good rule of thumb. Blindly changing features to make them less skeuomorphic is likely to make the product worse, not better. How to implement features in a shipping product such as Google Calendar should be based on usability, not whether you think the designer's thought process reflects a certain heuristic, overdependence on which has historically inhibited the emergence of new and better designs. Research efforts should be criticized on that basis, not shipping products.