On Fri, 24 Jul 1998, Nick Leifker wrote:

Very easy case in point: What would be the likely result if I were to go
in to work wearing a white lace blouse, skirt, pantyhose, and heels?
Conversely, how would society view a woman who wears a man's dress shirt,
slacks, and wingtips every day?  The problems become even more complicated
in Japan, where even the appropriate language is clearly separated by
gender.  This is what Ranma has to learn: the daily ins-and-outs of living
as a Japanese female. 

Considering that just by wearing his Chinese clothes instead of the school
uniform, Ranma's breaking a clothing taboo, and considering that Ranma already
pretty much wears unisex clothes, there's no reason why staying female would
change what he wears.

Besides, Ranma's as unused to "male" clothes as to "female" clothes.  Learning
to wear a business suit would be just as hard.