You are used to viewing the world through eyes with your own specific interpupillary distance (IPD), whereas if you were to look through the eyes of a mouse the world would look massive. So if you think models often look too small, you may have a lower than average IPD. I'm the opposite - most of the time models look too big. It's impossible to make the image look perfect for every viewer with current tech, but you can adjust scaling to an extent in the player.
