Why would a huge space station fire micro torpedoes? That sounds ridiculous. I always assumed they were the same "Spock coffins" as the rest of Trek.
Because those turrets are not big enough to host full launchers. The lauchers on the Galaxy are 20-40 meters long. Perhaps the choice was between putting an inferior "glued on" short range, slow rate of fire full size launchers (like on a runabout) or putting micro torpedo ones that have high rate of fire in order to repel amassed enemy ships.
I'll look into it when I get a chance.
I do agree that it's a bit ridiculous. They shoud have installed full launchers all around the outside docking ring and pylons instead of bothering with rotating turrets.