While Wired magazine has commented on the huge popularity of xkcd, it has not been able to provide a reason for this:
This mix of brains and fun, as well as underlying sweetness helped propel xkcd from a hobby to a full-time job for the 23-year-old former NASA roboticist. Since its 2005 launch, xkcd has grown from doodles in the margins of a graphing notebook to T-shirts, radio talks and lectures on humor at MIT, where students batted inflatable raptors around the auditorium. The website drew between 60 million and 70 million pageviews in October, Munroe says, and xkcd’s growing fan base has taken to re-enacting events that take place in the comic.
However, even I don’t have a clue just why it is that xkcd seems to appeal to people so much. So I asked my good friend Neha Natalya Pandey to put fundaes on this. Since she’s majoring in Algorithm Analysis and Design (and minoring in Sanskrit Poetics) at U. Mich., and she has an amazing intellectual pedigree (her parents are Dr. Acharya Somuchidononanda Pandey and Dr. Valentina Dimitrieva Pandey), she’s ideally suited to explain this. I reproduce her correspondence on this subject below, with her permission.