One problem I've always had with the armed forces is the double-standard there is in the military relating to head-shaving and gender.
All men entering the military are required to shave their heads. This serves several functions. It helps control hygiene. In the close quarters communal living environment of basic training, it is important that each recruit be clean and free of lice and other parasites.
Head shaving also has a psychological impact. The change in appearance helps facilitate the change in identity that occurs during basic training. It also helps in fostering a team-spirit which carries the individuals as a team. Head-shaving is also common among sports teams for the same reason.
The problem being that female recruits are not required to shave their heads. They are required to keep hair pinned up and off of the collar, but that is hardly the same.
I've never been in the military but I grew up in a military community and I've heard this discussed among soldiers often. Most of the men feel like women should be required to keep short hair just like the men, and for the same reasons.
I believe requiring women to keep short hair would also, in the long run, aid the women in their search for equality in the military. As long as there is a separate set of rules for women, they will never truly be considered as equal.