I agree with your assessment -- utility with respect to time is the first explanation I thought of as well. People (and firms) have a limited ability to anticipate or defer purchases. (I can't wait 50 years to buy a lifetime supply of food to feed myself!)
You also mention that this limited ability to defer purchases in the face of deflation is what makes short bouts of deflation not catastrophic -- it is somewhat difficult to get the deflationary spiral going if you can't actually wait to purchase things.
Given all this, the interesting question to me is, how much deflation does it take to actually cause a deflationary spiral? The answer is likely complicated, given that it depends on the specific utility functions for each consumer of all the goods and services that they consume.
Empirically, we seem to be able to cope with a decent amount of deflation, at least when it is limited to certain goods, like video game consoles, computing power, other manufactured goods, etc. (In some cases, even over very long timespans.)
The question is really what's in the average bucket of things you will put off versus the bucket you won't. One important note here is that the bucket off things you can put off is roughly proportional to the advancement of your economy; most of the goods purchased in a first world society can be put off more-or-less indefinitely. On the other hand, perhaps society's expectations for its standard of living have risen, forming a utility curve that's been shifted a bit. Another way to put that is that the worst case is that the economy runs at the level where everyone is willing to live; that's a sort of consumption floor. I'm not really sure what the answer to that is, but since I believe it's quite a bit below where we actually live, I think the deflation spiral is pretty real.
One specific observation here is that short-lived deflations may not cause much behavior change because everyone expects them to be short lived. And changing your behavior is hard work, and your standard of living is sticky; you don't adapt right way, even if you're a business. Easier to just ride it out. But as the deflation period drags on, that consumption floor starts to fall (everything here is mutable!) as you get acclimated to the new normal. Since consumer confidence actually lags the other economic metrics a bit, an economy has a bit of time to pop out of deflation before the spiral really sets in. On the other hand, it makes it worse when it does.
It's also important to look at context: in that empirical evidence, we should note that the central banks were fighting deflation as hard as they could withe somewhat limited tools they had, so it isn't a spiral in a vacuum. Even then, Japan lost an entire decade of economic progress to deflation.
On specific items like video games consoles and computing power, I'd guess it's some combination of a) the utility of the items actually being quite compelling at their launch prices and b) a trick of psychology: in 10 years, there will be new, better video games and you'll want those instead, so you don't even really consider buying it later. (b) is irrational, because the console you're buying now is either worth it or not now; you don't actually have to buy it later at all. But it strikes me as very human. I think public has largely just accepted the premise the technology costs a certain amount; it just looks forward to having new features that fall into its locked-in price range.
On the other hand, one way to think about the technology stuff is that perhaps it really has held back a lot of the industry. For example, perhaps the price of the Xbox is artificially low at launch time because otherwise everyone would just wait for it to come down anyway; it's competing with its future self. The thought experiment is to ask how different purchasing decisions would be if an industry-wide announcement came out saying, "Moore's law is over. This is as good as computers get. They're going to cost X and do Y for the foreseeable future." Because I suspect a lot of people do put off technology purchases, waiting for everything to get better and cheaper. The complement of early adoption.
I should caveat that this is basically all speculation on my part; I don't actually know anything about any of this stuff.
You also mention that this limited ability to defer purchases in the face of deflation is what makes short bouts of deflation not catastrophic -- it is somewhat difficult to get the deflationary spiral going if you can't actually wait to purchase things.
Given all this, the interesting question to me is, how much deflation does it take to actually cause a deflationary spiral? The answer is likely complicated, given that it depends on the specific utility functions for each consumer of all the goods and services that they consume.
Empirically, we seem to be able to cope with a decent amount of deflation, at least when it is limited to certain goods, like video game consoles, computing power, other manufactured goods, etc. (In some cases, even over very long timespans.)