Does anyone else actually like the visual design of HN? Besides the endless horizontal text problem, it's very easy to read, and there are no distractingly bad UI elements. Good minimalism, to me.
HN's design currently delivers a solid performance and its content is great. Looking a bit strange to passersby is probably a good thing, I don't think HN's focus is attracting new people, especially new people who are only attracted by the visual design.
I have no idea why the visual design of Stack Overflow is called horrible. It's ok, not awesome but certainly ok.
By the way, in that section I was talking purely about visual design, i.e. styling, or "eye candy". I'm not debating the fact that both sites have great user experience (in fact that's specifically why I picked them as examples).
I think you're right, trendiness does play a big role in style. And it's also true that complex designs generally get outdated faster than minimalist designs (see: 100% of Flash sites made between 2000 and 2005).
On the other hand, it's harder to brand minimalism. So like every design choice, it's a trade-off.
I regularly hear designers bitch about Linux, citing the command line as an example of terrible UI. That's fucking wrong. The Unix command line ecosystem has a fantastically good UI for its audience. (Grep is my homeboy.) It's just that the audience isn't your average design school student.
There's no such thing as "good design". There's only good design for your audience. What designers often call "good design" is really "good design for lightweight consumer products".
Yeah, to my mind this is bullshit. Reddit is another oft-quoted "horrible" design. Yahoo, msn also. It almost seems as if all the most popular sites on the planet are "horribly designed". Almost by definition this can't be true.
Personally I find both HN and SO great in terms of design. They're extremely easy to navigate, functionality and calls-to-action are clear and obvious. Data is presented in a meaningful and easy-to-read uncluttered manor. I'm not a design student (by any stretch of the imagination) but for the life of me I wouldn't be able to begin to guess what's so bad about either of these sites, unless it's the lack of super-whizzy glossy css3/js/ajax/flash magic that's the problem. Which is absurd, and only really relevant for "creatives".
Disclosure: I didn't read the article, so if it states why they're so bad I've missed out!