Tim - thanks... that was THE joke I just needed... shows brilliantly how irrelevant and ridiculous the physical attributes actually are.
Coloured belts derived in early shotokan karate of Britain to motivate the students as far as I know it.
And just for the record - in our dojo one can wear the hakama from senior student status - which in our dojo is from 3rd kyu. The best thing is that our wonderful sensei made hakamas for all us just before that test
But in estonian main dojo you are allowed to wear hakama from 1st dan.