I used to wonder that also, but I think it's because she's still a child.

The Black Cauldron isn't as popular as say Beauty and the Beast and Snow White. All of the princesses are from generally popular Disney movies

The Black Cauldron was an absolute box office failure,
and its one of disney's worst classic films, if not the worst. All of the Disney Princess movies are big box office hits. That's why they made Mulan a disney princess even though she is not a princess in the movie- she was so popular.

but eilonwy IS a real princess. not belle or cinderella

Belle & Cinderella became princesses, plus their movies were a huge hit. Disney is not going to promote a movie that is a failure.

Yeah, for all the reasons above, she is a bit to young, i think people like to look up to someone, not a person the same age if that makes any sense...?

I just think that she's too young. But she is a real princess, and I do like the Black Cauldron.

...

She's not in the public domain or Disney-owned. They'd have to pay royalties every time they used her.

She was part of a financial flop, and the princess franchise was created to sell products. She would not have been a good addition if one wanted to make money.

she's a princess Mulan's not even a princess

I havent seen the whole movie so I dont really know so much about her.

I couldn't resist the picture of that dog :P but anyway, considering I haven't seen it I can't really judge it, and I don't really know how well she would fit in.

No because she is too young, she doesn't sing, and her movie bombed. I agree with everyone who said that Disney is not going to promote a movie that was a failure.

I think people don't realize is there are certain requirements to be a DP. Ellinwoy was supposed to be apart of the lineup, but her movie failed in the box office. Being a "real" princess however, Cinderella and Belle are real princesses since they married princes.