Originally the lead character of Star Wars was going to be a girl, but George Lucas figured the world was not ready for a female lead so he split the character up into two characters, twins separated at birth.
There were other female characters besides Princess Leia in the Star Wars franchise of 30 years. http://starwars.wikia.com/wiki/Category:Females
The Empire Strikes Back was written by a woman:
http://io9.com/they-mocked-her-science-fantasy-then-she-wrote-empir-489586578
Yes Lucas had plans for Leia to go through Jedi training just like Luke. But the script writer had other ideas for her. In a planetary romance with Han Solo, leading the Rebellion against The Empire, fighting The Empire while buying time for Luke to train as a Jedi by pushing The Empire back.
You see Leia is a Princess but not one of those Spoiled American Princesses we see in SJW videos, she is a true leader and leads the rebellion and keeps it together and doesn't have the time to go through Jedi training because she is busy with other things.
Half of the movies she doesn't even know she is Luke's sister and doesn't know she can become a Jedi. Darth Vader reveals it to Luke and says if he can't turn Luke to the Dark Side, maybe he can turn his sister.
In Return of the Jedi, Leia leads a plan with Luke to rescue Han Solo from Jabba the Hutt, and then leads another plan on the Moon of Endore to take down the force shield that protects the second Death Star.
Leia didn't have time for Jedi training, she was leading and planning a war against The Empire and it worked, they won. She had no interest in learning Jedi training.
It wasn't until the Millennials were born that girls all of a sudden got an interest in Star Wars and comic books and all of that stuff.
In the Prequels there were a lot of female Jedis. Even more in The Clone Wars, and Anakin's apprentice Asoka was more powerful than you'd think. But these Social Justice Warriors maybe never watched the prequels or Clone Wars? Not even that Star Wars: Rebels show where two of the members of the Ghost crew are female and we see Asoka survived the slaughter of the Jedi.
I don't know why Disney did a Rouge Squadron where most of the pilots are male? Except that I remember the original Rogue Squadron was all male in the video game and the books.
Disney is trying to appease the social justice warriors that want more diverse characters. But because the diverse characters in Rogue Squadron are mostly male, they throw a fit.
Look Star Wars was mostly targeted at young males in 1976, it was a different time, a different place. They found that it didn't appeal to females.
The prequels were rewritten to appeal to females, which is why they were so bad. They had them more soap opera than action. Lucas tried to get stuff to get more females into the franchise but he didn't know what females liked and ended up ruining the prequels.
Disney wants to go back to the classic formula in the 1976 film that did so well. It is a business decision they made. They have made all new diverse characters, you got an African-American Stormtrooper for example, and most of the movies you never see the person under the helmet.
The next film they are keeping quiet over so they don't spoil it. Leia might have gone through Jedi training like she did in the books after Return of the Jedi, and if she did they are keeping quiet about it. If not then she had children that did Jedi training and at least one of them has to be female. So they cant show a picture of her with a lightsaber, it would ruin the surprise if in the film she is a Jedi.
Obi Won Keonbi had lied a lot in the 1976 Star Wars: A New Hope film. Not telling Luke that his father is Darth Vader and had murdered 30 Jedi children with his lightsaber and he left him in a pit of lava with an arm and leg chopped off to die. That Leia is his twin sister and their mother died in childbirth. That the Jedi had them separated to keep them from Vader. But in all honesty in 1976 they had no idea were the story was going to go or even if there would be a second movie and didn't even have a script. Just that Kenobi was a general in a clone war and Jedi Master.
Hey I don't complain about the countless Chick Flicks out there that are mostly female characters and if there is a male character he is a romantic interest and usually very stupid and basically a Ken Doll to their Barbie dolls.
You can watch Star Wars movies and TV shows, you can read the comic books and books, you can even play with the toys and other merchandise.
Disney got a complaint that the Darth Vader costume was for boys only so they made all of the costumes unisex. So girls can wear them too.
Here is a cut scene where there is a female Sith Lord/Lady:
http://www.youtube.com/watch?v=0X9NFknjTRE
She is like Darth Vader but female. It was cut from the original movie like many other things.
The Avengers are mostly male yeah, just like it was in the original comic book. Marvel made an A-Force team where all of the members are Female and lead by The She-Hulk. http://en.wikipedia.org/wiki/A-Force
It hasn't made it to the MCU yet.
Disney is going to have more female characters in the MCU films. Age of Ultron brought in The Scarlet Witch. There is still Ms. Marvel, She-Hulk, The Wasp, and many others they could use in the future.
If you do your research you find that there are more female characters than you think there are.