I was always disappointed by the generic racial garrison units in each colony. It always felt like there should have been a tech or building that automatically put a basic mod on your defenders. Defenses are usually a waste of production in multiplayer, so a little buff would be nice.
Adding defensive mods also makes your colonies more unique, because they will reflect your secret tech. Synthesis integration was a good first step, but all techs should get a little something.
I really liked that all the racial turrets used the racial weapons and had slightly different damage and even debuffs.