It's the same as the cover girl concept, cos, most of the people will have attendion on Female more than Male, no matter the reader is male or female or not >?
In addition, most of the boss is male more than female, and they seems like employ young female more than male.
Reason ? You no need to care the reason, the reason to each boss is also different, and the last factor i think is that:
Generally, the school result of female is better than male, so the male can only work for some kind of heavy job, and female can work for this kind of office job. (Relatively)