Maybe MOE has...

... a ponytail fetish.

http://www.plmgss.moe.edu.sg/website2008/announcement/SchRulesNReg.pdf page 2 of this,

3.2 If hair is kept long
(that is hair beyond the
second collar line but
above the first line of the
school pinafore), it must
be neatly tied in a
ponytail or bunned with
a proper hair net.

Ever wonder why ponytails? Maybe.... something like this happened...

''The sexiness of the nape of the neck found in short hair. The gentle femininity found in long hair... A ponytail perfectly combines these two seemingly contradictory elements. In spite of these, lately we don't see girls with ponytails around anymore... T_T...''

''Good, i have the same idea. Lets put having ponytails as one of the rules, although there's really nothing it has in relation with disicpline and respect.''

'' I like buns. Lets put in buns too.''

Perhaps that was the discussion when they were deciding school rules.