It’s far from exclusive to Hacker News. In fact, it doesn’t seem to be that prevalent here, as when it’s mentioned it at least tends to be in relevant context. Reddit, Tumblr, Imgur, and plenty of other communities both on and offline have an appreciation for Japanese culture.
> although I've come to realize that it's mostly Americans holding up an example of everything they feel they lack domestically, and in that sense isn't so much about Japan as it is about America
Also not related to America at all. It’s just as common in Europe and western countries in general. Generation probably plays a role. Find anyone who had their mind blown by an anime at a formative age, and you’ll find someone who to this day is likely to have some degree of fascination with Japan.