I believe girls should learn martial arts and such self defense techniques. They should be able to atleast protect themselves in case of danger.
Infact every parents must make sure their daughters are at least aware to deal with the unsafe situation. It is not necessary that every girl who learns martial arts will turn bold and arrogant or become like boys. Martial arts will in fact will boost the self confidence and make their brain and mind aware to deal with the situation. Parents cannot protect their children all the time, children should also learn to deal with the unforseen circumstances.