Despite how safe and formulaic Disney movies eventually became, Walt was a risk taker who did experiment with different kinds of animation. Movies like the Skeleton Dance,
Fantasia, Song of the South, and one of my personal favorites The Three Caballeros. And pretty much anything Ward Kimball directed or had a hand in at the studio. Here are two Kimball movies that won Academy Awards!
"Toot, Whistle, Plunk and Boom"
"It's Tough to be a Bird" and educational movie, but awesome. Look it up and watch it. Big time fun factor.
Ralph Bakshi is another fellow who pushed animation into new territory. His collaborative work with legend Frank Frazetta on "Fire and Ice" is my favorite of his work and a must see!
The point is Animation is a medium not a genre, it can be used in any genre.
More recently, I thought "9" was a very good, dark, and not child friendly movie. I am looking forward to the director Shane Acker's new movie "Beasts of Burden" and any other movies that want to break the current mold of animation as strictly a family friendly medium (even though I do have a soft spot for the looney golden age stuff).