You're being cast for your acting ability. It's not based on the way your body functions. If you're playing a lead in a movie, it's for that character and they'll tailor it to you. In a dance company, you have to fit in a definite mold.
“Life is a corrupting process from the time a child learns to play his mother off against his father in the politics of when to go to bed; he who fears corruption fears life.”