It would need a lot of these devices for the odd mW to really make a difference. It adds up, but it's in the ballpark of a router's status LEDs. These costs are

It would need a lot of these devices for the odd mW to really make a difference. It adds up, but it's in the ballpark of a router's status LEDs. These costs are already accounted for as part of the device's operation. Critical systems might start to better direct their transmissions and to reduce side bands instead of saturating the area with energy.