Can we have hakama?

[kyuven]

What do you mean? I wear it three times a week during my kenjutsu lessons, but my posture does not change.

You don't really notice when you're actually wearing it, but looking from the outside someone's standing posture changes slightly.
Hell if you wear them long enough your basic standing posture changes!
Also, remember what you have to do to sit down properly.

Basically, it would either look awkward on the character models, or require reworking them.