I've been pondering this issue a bit, and briefly looking through articles on Wikipedia, and I agree series boxes are overused, but think they are valuable in some places. The basic crux of the matter seems to be that they are useful when the article is integrally part of a series, but are often used to essentially construct series where no actual series exists, and where things would be better served by a "see also" box. This has some point-of-view implicates as well as simply being irritating, because "claiming" things as part of a particular field or line of work is often not uncontroversial. It's also nearly impossible to do in a clean and universally-agreed-upon way (are articles about the human mind part of a psychology series or a cognitive science series?) and clutters up the articles, so is best not done, I think.
Examples where I think a series box is a good idea are the country history articles, which are broken down into periods. These are clearly part of a series, as there is basically one very long article on the history of the country that is broken down largely for convenience. [[History of the United States (1789-1861)]], [[History of Poland (1939-1945)]], and so on.
Here are some where I think it is bad: * [[National Rifle Association]] -- This should be a stand-alone article. If you want to link to other pro- or anti-gun groups, that should be at the end, in a "see also" section. * [[Electronic music]] -- Again, this is properly a "see also" matter, as classification of music genera is hardly as straightforward as the box implies. * [[Cultural studies]] -- Arguably large parts of cultural studies aren't even part of [[critical theory]]; at the very least, it's not a clear hierarchical relationship.
In short, I think we ought not to use series boxes except in very isolated cases where there is very clearly an unambiguously actually a series of articles. In other cases, the old standby of "see also" links is much better and makes fewer controversial claims of subject hierarchy.
-Mark