Here is a link to a wonderful post on emotional singing by vocal teacher LoVetri. I totally agree with her conclusions.
If someone sings with power and technical perfection, yet without authentic emotional feeling, the performance is wasted. Yet emotion without training can wreck a voice.
The voice must elicit some kind of emotional response to be effective, yet no one listens very well when someone yells at them. Balance, dear singers. Balance vocal training with the courage to sing from your deepest truth.
Set yourself up correctly, know what you want to communicate, intend the message and support it. Let the song sing itself out of you. It's amazing when this happens.
Here is Ms LoVetri's article:
LoVetri Post: Perfect Vocalism