Shan, I agree with you completely. That's why my comments were just descriptions of what happened in the films and nothing else - no judgment calls, no offense, etc.
In ROBOTS (not Roberts, as I previously wrote. What the hell was I thinking?), I do think it's because the character was male and did not want to be perceived as anything else. In fact, early in the film Williams' character lets Ewen McGregor's (Did I spell that right?) stay in his room, saying "Not that I want to get the gossip mill going." So in that movie there was a bit of a statement.
"Mulan" is an excellent Disney carton taken from Chinese history and legend. It tells how a young lady disguised herself as a man to fight against the Mongols. Her father, while not "old," was not physically up to the task, hence her decision. And as for dressing soldiers as concubines, it was done as a way to get into the palace to rescue the emperor.
Again, these were just general observations and no opinions attached.
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