Ryunosuke Akutagawa remains something of a literary anomaly. A major stylist, he is denied the established standing of a Natsume Soseki or a Shiga Naoya. Instead, he is relegated to the role of eccentric, a minor symbolist who wrote a few popular pieces.
Perhaps this very popularity works against his inclusion in the establishment. He is comparatively easy to read and there is correspondingly less for a literary scholar to do. In addition, he is an extraordinarily imaginative writer, even a fanciful one, and literary opinion in Japan has long been controlled by the various schools of realism.
He was also an antisocial maverick, and this did not endear him to the literary establishment. Even the fact that he committed suicide -- usually enough to ensure instant canonization -- has not been sufficient to earn him a place in the local literary pantheon.