No one can deny that limericks are a highly amusing, often pleasingly vulgar and very popular form of
light verse.
Making a comparison between one poetic form and another, though, verges on the absurd (which, I expect, was the very point of the jest presented above — yes, if it was a joke, I got it).
If this nodelet is at all in earnest, though, I strongly suspect the Japanese speaker interrogated in the preceding account was trying to politely detach from an absurd conversation with an unpredictable Westerner. It could also be the case that serious verse is no more popular in Japan than serious forms are here in primarily English-speaking nations.
Each poetic form does something different. One easy pitfall for Westerners reading haiku is that they understandably may imagine that a haiku rendered in English (or any other Indo-European derived language) is somehow equivalent to one written originally in Japanese. Another bar to understanding would be the inevitable debasement of the form that comes, at least for victims of American public schooling, since practically everyone who has attended an American public school has at some point been required to write a "haiku" in English, and therefore thinks they know far more than they do about the form. American students are also, through no fault of their own, subjected to countless pseudo-haiku written for no other reason than because it was a school assignment.
Haiku in English is not haiku. The subtleties of haiku (and others less-familiar forms of Japanese and Chinese poetry) derive, in part, from the structure, the density of meaning, and the huge range of phonemic associations that can be stirred by the nature of the languages in which these forms arose. The form is well-suited to the Japanese language, whereas, in English, even the best haiku imitations are likely to be thin and inconsequential by comparison.
This difference is something deeply rooted in the structure, and density of language that a character-based language permits. Punning on phonemes is not something easily done in English. It is second nature in a character-based language and its organic poetic forms.
If you choose to explore Japanese and Chinese poetics, try to ignore Fenelossa and Ezra Pound. Their ideas about Chinese poetry are fascinating and evocative, but are based largely on ignorance of the Chinese language and flights of poetic fancy. They are influential and worthwhile works as English-language texts on English poetics, and they continue to have considerable value in that sphere, but their linguistic validity as an analysis of the poetics of the Chinese language — and, by extension, of Japanese and other languages that have borrowed the Chinese character set — is practically nil.
Though far from perfect, Douglas R. Hofstadter's Le Ton beau de Marot: In Praise of the Music of Language is a good place (especially for those of us with traces of geekishness) to look at the difficulties, challenges, pitfalls and near impossibility of poetic translation.