Well... when O-sensei started Aikido, all his students where Hakama, if I'm not mistaken that is.
In our organization, women of 3rd kyu could start wearing Hakama and, for men, 1st dan. This bothers none.
Just remember, when one starts wearing Hakama, there is a responsibility that comes with it. Many only treat it as a piece of fancy clothing, but in Aikido the Hakama worn is the Samurai's Hakama. "What's the difference?", one might ask. The Hakama that is worn for an Aikidoka has 7 folds, each representing the 7 pillars of Budo. The Iga Hakama that is worn by Ninjutsu practitioners has no folds at all, to them such code is pointless.