The Quadra 700 automatically detects whether ROM SIMM is installed or not. I would guess it uses one of the ground pins to detect it or something. It's possible that the newer Macs don't need the jumper.
The Quadra 840av has these ROM SIMM pads too. I have a Quadra 840av ROM SIMM and unfortunately its pinout is slightly different so it won't work with my SIMM -- the 840av's motherboard presumably supplies 5V on the ROM SIMM chip select pin which would deactivate it. (It must because 840av ROM SIMM has the chip select pin tied directly to 5V). Probably wouldn't hurt anything but the chips wouldn't respond correctly without a hack done to the SIMM.
The Quadra 840av has these ROM SIMM pads too. I have a Quadra 840av ROM SIMM and unfortunately its pinout is slightly different so it won't work with my SIMM -- the 840av's motherboard presumably supplies 5V on the ROM SIMM chip select pin which would deactivate it. (It must because 840av ROM SIMM has the chip select pin tied directly to 5V). Probably wouldn't hurt anything but the chips wouldn't respond correctly without a hack done to the SIMM.