Re: who can wear hakama
I think there is a difference between prewar and postwar attitudes.
Whereas prewar, and immediately postwar for the deshi (e.g. Saotome-shi), hakama was a garment covering underwear and so was worn as a matter of course, after the war in the Aikikai it became a mark of rank and was tied to the gaining of shodan rank.
In the dojos I look after in Europe, some instructors allow 1st kyuu students to wear the hakama. However, when I go to Europe to give training courses and deliver shodan diplomas, these students have to train in white belts and with no hakama and, immediately after receiving their dan diplomas, they have to remove their white belts and put on their hakamas in front of everybody. Then we continue training.