I think there's a difference between making software that looks pseudo-physical like Aqua, skeuomorphic like iCal, and mimicry like all those digital representations of a business "desktop", complete with 3d in and out box and useless paperclip holder...and I think that these things lie on a continuum.

For example, an audio recording app might start with a simple default OS "record" and "playback" buttons. Add shadows on the buttons and brushed aluminum for the window dressing and just look pseudo-physical, start adding 70s era cheap plastic looking knobs and you rapidly slide into skeuomorphic, keep going and next thing you know you hit Apple's podcast app, a little more and you go full Microsoft Bob and make you drag a virtual tape from one reel to another, through all of the various other windy rotating bits that are present in an actual reel-to-reel tape machine.

Skeuomorphism works when it dresses up a boring interface that's more or less feature complete. It might even go so far as to evoke the feeling of a familiar real-life object...paying it homage rather than mimicking it.

What doesn't work is when you rely on mimicry in an application to guide the user into the digital world from the physical one by employing a similar looking usage pattern. It sounds counter-intuitive, but it's true...why? One person's familiar metaphor may be completely outside of another person's experience. Take your example, Electric Checkbook, many people under 30 have probably never even written a check, or balanced a checkbook! I'm over 30, and I don't think I've ever even finished off an entire book of checks in my entire life! It's just a metaphor that no longer has relevance. I do lots of banking, pay bills, mortgage, car payments, school loans, utilities, etc. But I simply have never needed to use physical checks in anything but the rarest circumstances. For people in their 20s, they may have never actually even seen a physical check! The app may as well be designed around sectioning 8ths of Gold Doubloons and measuring out gold on a balance scale for all the relevance it has to new users!

Similarly, iCal looks like no timekeeping/scheduling object I've seen outside of professional offices of very senior executives and lawyers. Most people just don't use leatherbound desk calendars anymore. It doesn't evoke familiarity or nostalgia because it's simply entirely outside of most people's personal experience. Where iCal gets away with it is that it's fortunate that other calendar apps that computer users have become conditioned to over the decades are skeuomorphic in the sense that their design and layout are very much in-line with the layout of physical calendars anyways. But there is no reason a calendar can't be laid out in a wheel, or a list, or some other interface paradigm, and made to look like it was scratched into copper or some such and just been pseudo-physical.

The reel-to-reel "Podcasts" similarly tries to evoke some kind of nostalgia factor, listening to authoritative news reports on a vintage tape machine, without stopping to figure that most users have probably never even seen a "real" reel-to-reel. It's not skeuomorphic, it's Bob. It's so bad that the builders of the app didn't even bother building in the necessary functionality into the software before blasting faux-nostalgia vomit all over the design. At least I don't have to run the tape to setup the playback.

More importantly, design that's on the Bob side of skeuomorphic design almost always fails to scale. A bookshelf metaphor is fine because it's close enough to a basic grid of book covers, with a little wood veneer on it when a library has a few dozen titles in it. It blows up when you start having thousands and spend minutes scrolling through shelves trying to find your title, when a simple alphabetized list would have performed the function better. (The Bob way to solve the problem would be to organize your titles by the Dewey Decimal System, then give you a virtual card catalog, complete with little drawers full of little faded cards you have to comb through...and again this would present a physical metaphor for an experience completely outside of most people's modern experience in the last 20-30 years).