Broomstick, I don't know that Toni Collette is only thought of as playing mentally unhinged character. Her Oscar nomination is for playing the character who was the only sort of sane person in the film, in IN HER SHOES (where she's underrated but fantastic) she is the stable sister, and I doubt she was unhinged in her last two movies--FRIGHT NIGHT and HITCHCOCK. She was incredible in US OF TARA, and maybe because she's not afraid to "go there," people think of her as very capable for Diana. It's kind of like with Naomi Watts, probably the most intense Hollywood actress of her generation, she's just really great at playing ridiculously intense characters. I don't know that it's a bad thing.
I love hearing movie stars tackle the musical theatre cannon in the context of a movie musical, it's fun and different. I love hearing Streep's singing voice, she can act a song like few can and from what I've read from people who know about this stuff on the board, her singing is very technically proficient. However, Diana is a role that needs that great vocal performance to match the intensity of the material, it is true that Collette is probably the only movie star who has the vocal power to do justice to the role.
"Some people can thrive and bloom living life in a living room, that's perfect for some people of one hundred and five. But I at least gotta try, when I think of all the sights that I gotta see, all the places I gotta play, all the things that I gotta be at"
