Let me continue the conversation with my personal account.

When I write a haiku in English, I also prefer the 3/5/3 form (following Keiko Imaoka), but in 33 editions of Mizu No Oto contest I noticed many English speakers are used to think about haiku as 5/7/5.

I was needing some objective parameter, since this is a competition, in order to not leave judgment to purely emotional and subjective considerations. I know this is both a simplification and a schematisation of what a haiku could be, but I think it's inevitable if I want to keep a transparent contest.

On the other hand, we always accompany the contest with brief theoretical reflections on the aesthetic categories of haiku. These reflect my education on the subject, which starts with a study of classical Japanese haiku. This means that the setting of the competition is a bit special.

Regarding the metaphor and the "aha moment", these aren't concepts I often found in my studies. I think I understand what "aha moment" means in English language haiku elaboration: it's what I'm used to call shizen (I'm talking about it just in this post).
However, I disagree in using metaphors, or other rhetorical figures, in haiku, whose language should be immediate, sober, everyday and unadorned.
Also the concept according to which the haiku should be a metaphor of the human condition does not find me in agreement, since this in my opinion falls more in the concept of senryū.

Obviously I don't pretend to teach anyone, but it seems to me correct to let people know that, in the context of this contest, these settings of mine influence the judgment on the winners. :)

P.S. I do prefer your last, briefer, version :)