What it really comes down to is I love to connect. The voice is the primary way we connect, not only through our words, but our tone, phrasing, inflection, and timbre.
My voice teacher shared the most amazing idea with me recently: when a singer gives a performance, their music is released from their body as molecules, which are then dispersed into the surrounding environment and absorbed into the bodies of the listeners, mainly through their ears, but also through their other senses, skin, and energy. A part of the performer is literally becoming a part of the audience. HOW AMAZING IS THAT??!?!?!?!?! I had never considered the voice this way before.
Through performance we connect. Via these musical molecules, we literally connect our physical and mental selves with other people. What more beautiful practice could you want to participate in! I think many (if not most) people consider music to be spiritual on some level, however they choose to define it, but this explanation of the voice really tops it for me. The voice is my mechanism to connect to those around me, to love them, to share myself with them and vice versa.