The periscope eye display is a common feature for many systems of this ones class but it inhibits peripheral vision which is why its often mounted to flip out of the way. At this point in time most smart glasses are to weak to take a combat troops abuse but that is changing slowly.
The function of such systems is not as simple as you make it sol. They are often used to display navigation, text communication, thermal and IR imagery, relayed imagery from off site like feeds from drones other soldiers or maps from command.
Another common feature for systems of this ones class is shooting around corners. This is done by feeding imagery from a camera mounted to the carbine of the soldier to the display. So that the soldier can aim there weapon at a adversary from behind cover without risking their lives.