because she wasn't so upscale.

She brought Disney back from their mediocre to bad period. She helped being back musicals and kind of started the modern way of telling an animated movie.

or Ariel. Disney said that if it wasn't for Rapunzel's success, they would've taken a break from princesses

Basically what Jayden-G said. And she broke away from the classic mould of the previous princesses.

I noticed this is turning out to be like the important DP movie countdown. It's not really about the Princess.

She sparked the Disney Renaissance.

She started the Disney Renaissance, and because of her, they probably sold a lot of merchandise, because every little girl wanted to be a mermaid as well

Yeah, the movie itself does have a part in it as well.

Started the Disney Renaissance

She helped the company alot, starting the Disney Renaissance after a rather bleak spell of movies.

And Rapunzel