One can only sing as well as one’s control over the voice allows. If there is a weak place, or places that are tight, the singer will either be limited or sing badly. Period. The reason to work on perfecting technique is because it allows the singer to sing, and sing freely, with artistic expressiveness.
Emotionality in music, or the ability to allow the voice to actually carry genuine emotion, should be the goal of any good singer, no matter what style they sing. This is what people respond to, what makes the music alive and vital, and what makes for unique and memorable performances. Anyone’s voice can be emotional if they are experiencing strong emotion and making voiced sound, but using the voice healthfully in a powerfully emotional manner, over and over, in musical phrases that can be demanding on many levels, isn’t something the voice generally “just does”. It requires conditioning of the vocal muscles and the breathing mechanism, else the emotions cause strain and abuse of the vocal folds. Singing “with emotion” isn’t necessarily easy.
Musicality is the ability to find the expressiveness and emotion in music and allow it to move through the sound. It isn’t the same thing as being a good musician, although it certainly is hoped that those who are professional are both. Most people would rather listen to a singer who is musical (although the audience wouldn’t necessarily know if the person was a good musician or not), than to someone who is an excellent musician but is emotionally flat in delivery. Talent has to do with many ingredients, but musicality is certainly a strong component in any talented performer’s lexicon.
Classical training should set up the voice to allow great emotion to pour through the sound, but often this is not the case. There is often so much emphasis on the sound for its own sake, and so much attention paid to various versions of “correct placement” or “ringing resonance” or on breathing that actually feeling emotional during a sung phrase may never happen. Making a lot of sound is impressive, but I am not won over by such displays. I would rather be moved or touched during a performance. That happens when the voice is at the complete disposal of the artist and when the artist is willing to go deep within to a place of truth while singing. Simple but very hard.
Certainly some music, and some kinds of styles and performance, isn’t meant to be continuously profound, and the various levels of intensity that any performer feels may vary quite a bit. Emotion can be expressed through many avenues, in addition to the voice alone, and sometimes a simple delivery of words and melody is enough to make for a fun or light-hearted and entertaining performance. There are also performers who do not want to risk feeling really emotional while singing, lest the emotion overtake them and the voice, and make for chaos. That is what training is for, and it is a shame that such individuals don’t know what could be available if they were to look for it.
Teachers of singing should always find a way to investigate whether or not the student is in touch with actual, real feelings while singing, and whether or not the singer is capable of being emotionally free but in control while performing a song. The training process needs to be harnessed to feeling, and feeling happens in the body as both sensation and emotion. When these ingredients exist equally, it could be said that the singer posesses perfect vocalism.