He's a seriously important, influential French cultural figure (coining and popularizing the terms 'cubism' and 'surrealism,' pioneering modern concrete poetry) who isn't discussed much in English literary circles.
I recently read a collection of his works and I think he probably deserves to be considered one of the modernists. From art criticism to poetry about airplanes and total warfare, he was definitely an artist concerned with capturing and reflecting modernity. He was seriously injured in World War I and died during the postwar flu epidemic aged 38; I think he definitely had a lot of untapped artistic potential.
And beyond his historical importance, he's just a fantastic poet, a strong personality, someone who pioneered surrealism because he was fascinated by strange contrasts, by weirdness. #entertainment