Ashe and Moira I can see not caring and it doesn’t really fit their personality anyways. Widow is too villainous to be dancing. Ana’s knees can’t handle it anymore and she sleeps by 8pm anyways.
But why not Mei? Why didn’t they call Mei up?
It’s because of this, isn’t it?
Her body shape fails to meet the requirement and she isn’t an energetic dancer.