One of the great joys of modern electronics is the fact that they are never actually turned off, like your TV which is always on even when it's off.
So, in addition to the risk of the electronics getting fried by a power surge of some kind, the device is always using power to keep the little LEDs glowing. With some devices, it is not a problem to have them on a switched circuit that can be turned off to totally cut power to the device. But if the device in question has any memory for the settings or programing, this can be erased by cutting the power so that you have to go through the whole setup process every time you want to use it.
This circuitry has found its way into just about every woodworking tool that uses electricity. It used to be that a router had an on/off switch. Period. Now they are full of chips and circuit boards.
Going up the ladder, many larger machines are now incorporating electronic speed controls, table elevation and tilt systems etc. And when you get into CNC equipment, you are almost totally dependent on computerized electronics. It might not be too painful if the "brain board" in a router gets fried but on a big machine, an unexpected power surge can result in a very costly repair bill.
For this reason, many shops that are using this type of equipment are having to invest in additional protection devices or at least, installing switched circuits so that the machines can be totally disconnected from the power grid when not in use.