I think perpetuating the myth that all little girls need to do is to be pretty, and a prince will come rescue them from their sad little life and they'll live happily ever after is not desirable, it is damaging.
I realise that that is not solely down to the powerhouse that is Disney, but they certainly contribute greatly to that.
The Disney princess behemoth is simply insidious- it is everywhere, and ensnares girls from birth, trapping them in this false world where only beautiful things/people are good, women are subservient to men, the only goal in life is to marry and marry well, we can win things just by being beautiful rather than working hard for them. Don't get me started on the 'Barbie' books (non-disney I know). HSM? Pah- well if we could just perform our way through life, everything would be fantastic, world poverty would end, war would be over 
Disney is saccharine, falsely sweet; stories and characters with wide-ranging human characteristics are sanitised and divided into good and evil, white and black.
Fairy tales are scary, grim, odd, funny, cruel, disturbing, wry... but they are also learning experiences, to help children make sense of the world, and our history. They are also not aimed at 3yos, but older children. I cannot read "The Little Mermaid" (Hans Christian Andersen) without breaking down, and I certainly cannot read it to my daughter- the heroine gives up her life, everything she knows for the Prince she falls for, wants to marry even after only a brief glimpse of him, she even gives up her tail and gets legs instead, meaning she is forever barred from her home beneath the waves ... and then he abandons her and marries someone else the betrayal is staggering, and a small child cannot possibly comprehend the message in this story. I hate it.
Mulan however is a good film, with a strong female role model, who is driven by familial obligations that override gender, has to work extremely hard to succeed including overcoming prejudice- what messages would you not want your child to take from this film? Hell- I just love the songs!