We were promised that we will play as Garrett. The voice we've been given is not him. Stephen Russell, the voice actor for the first three Thief games, defined Garrett. Garrett does not have a defining face, it is his characteristic voice that makes him who he is. Change that, and he becomes another character entirely.
We've all gotten attached to that voice over the course of many robberies, adventures, and heists. Without it, Garrett is simply an impostor of his own self. A plastic Garrett lookalike. And so we urge the developers... Please bring Stephen back?
It might seem like a small thing to some, but it is not. Don't let Thief go the same way Splinter Cell went, which had its main character replaced by a new actor after five games. It is like a slap to the face. We've gotten attached to this character. Don't take it away. Stephen is a core part of the Thief series.