That is how it sounds, isn't it? Tranquil are just that. Tranquil- but not in the manner of someone at peace. They feel nothing. They cannot. They do not dream, they do not feel joy or anger, do not feel desire or fear. Sever a mage's connection from the Fade and they become someone- something else. They cannot cast- they cannot ignore an order as given. Their will is no longer quite their own for they have no desire to motivate themselves.

[ It was a horrible fate for anyone too afraid to endure the Harrowing. Something one of her dearest friends chose. The last thing he chose. ]

You do not need emotion to work with the fade- but they do play into one another. If it were merely a question of that anyone could use magic. There is an inherent connection bound by emotion- feeling too strongly may entice demons to you; maintaining focus, calm, and control while casting so you shape the world to your will as you intend rather than losing control is important.