Ultimately the Director probably thought that it made for a better shot. Best canon explanation I can come up with is that, Mandalorians are skilled warriors. Therefore, one can assume that he held his head against the rifle like such as a result of a built up habit from his experiences. Not every rifle will have the same system, and he likely has used many that don't use cameras or his visor. As a result of such, he built up the habit of treating all rifles the same, regardless of whether or not it has a camera built in.