|each fuel injector's electrical connection (which is a coil of copper wire to make an electro-magnet). The other connection of the coil goes into the ECU where it is grounded by a semiconductor (probably a FET type transistor) from a signal within the ECU.
The wiring design is very common for most of the electronic devices that we use day to day. Power is applied to the device (fuel injector in this case), but current does not flow through the device because the other side is not grounded yet (switch is OFF).
It is the same situation of + 12 VDC going into a switch such as the dome light switch, but the switch is not turned ON, so the current does not yet flow through the switch and to the light bulb, and then to ground. The logic is that some small amount of current does flow because there is not perfect insulation in a switch design, especially using a semiconductor as an ON/OFF switch.
The proposed design change would eliminate the + 12 VDC from being applied to one side of the fuel injector's coil until ignition switch (key) is turned to the ON position.
I think it is OK to do this...but not really necessary to improve fuel injector life.