d2d advantages remote start

I recently installed a remote starter my 2002 Pathfinder. I had a question in regards to the D2D ports found on remote starters and bypass modules.

My inital setup was a Avital 4113 + PKALL Expressit Bypass module.  Both units have a D2D port so they can link directly together.  The PKALL can also be hooked up by cutting the DND jack and connecting the red wire to 12+ and the blue wire to ground. The other two wires from the D2D pin are not used. All other wiring remains the same.

I am confused as to what the advantage to using the D2D port  is as wiring two wires instead of plugging directly to the remote start module doesn't seem like much. Am I missing something or is that it?