Why are there so many "in Wonderland" episodes?


Many series that I have seen have "x in Wonderland" episodes where they have
retellings/variations of Alice in Wonderland with the characters from the
show. Examples of this include Ouran High School Host Club (episode 13), Black
Butler (season 2 OVA 1 and 4), Cardcaptor Sakura (episode 55), and Code Geass
(OVA). What is the origin of this? Is there some sort of cultural basis for
this?




I guess this is because of it's overall popularity. According
[here](http://tvtropes.org/pmwiki/pmwiki.php/Main/AliceAllusion),

> **Alices Adventures In Wonderland is a pretty well-known work: it can be
> associated with world-crossing fantasy, drug imagery, lolita fashion and
> other aspects of Victorian England, political satire, and who knows what
> else. No wonder it shows up a lot in anime** , shock horror (it's a frequent
> target of Grimmification, usually with lots of blood), and emo teen novels.
> (You know the kind — usually involving vampires, eating disorders, or
> vampires with eating disorders.)

