Billy Collins writes of haiku in the introduction to Haiku in English, edited by Jim Kacian, ©2013:
Many people don’t get haiku. They typically ask what the big deal is about a frog leaping into a pond or a piece of green pepper falling off a salad bowl. So what indeed? Maybe the best answer is a slap on the face, a common “answer” to a baffling koan. But a more reasonable explanation of the “big deal” is the irreducible fact that the poet was there to witness the event. A cherry tree in blossom and a dog barking in the distance may not seem to add up to much, but what such a haiku declares is that someone was present–actually there, living and breathing–at that particular intersection of sight and sound. In that sense, haiku not only convey the beauty of individually experienced moments, they are also powerful little assertions of the poet’s very existence. Not to be present to witness the cherry tree and the barking dog means being absent, perhaps non-existent. Every haiku makes a common claim: I was there! Like Kilroy with his nose over the fence.