It's because the artist is popular because of his drawings (and for good reason; they're amazing). It's not exactly fair to people who are really good at poetry to be overlooked, but there's your answer.
Modern haiku style is full of shit. It's just a contribution (and maybe even a misunderstanding) from the anti-form crowd. There is no English equivalent better approximated to the Japanese "on" than the syllable. There's a very beautiful thing in sticking to the structure rather than going with the first thing that pops into your head, and that was one of the points of adhering to the haiku style in the first place.
It's not pointless; this is what a lot of people study and live for. I don't mind that your haiku is not in form. I just don't think it's right that someone would make an appeal to authority about non-form being the preferred method. Just because it's a trend that people do it that way doesn't mean it's the correct way now.