Why do Yudansha wear hakama

From http://www.guillaumeerard.com/daito-ryu-aiki-jujutsu/articles/why-do-yudansha-wear-hakama 

By Guillaum Erard

Origin of the association between Confucian values and hakama pleats Although the adoption of the Confucian values by the warrior class is well documented, the precise point at which the pleats of the hakama were ascribed these values is unclear and some scholars argue that it is actually as recent as the Meiji era.

Remembering that the origin of hakama lies partly in nobility, partly in shinto, the association of the Confucian (buddhist) values with the shinto piece of clothing provides an interesting illustration of the syncretism that occurred in Japan between the two thought systems.

Regardless of the origin of the association, some prominent contemporary instructors have extensively written on the topic, with for example Saotome Mitsugi who, in his book: The Principles of Aikido, lists them as:

Jin (仁): benevolence
Gi (義): honor or justice
Rei (礼): courtesy and etiquette
Chi (智): wisdom, intelligence
Shin (信): sincerity
Chu (忠): loyalty
Koh (孝): piety